overclocking intel celeron 366

First...if you're running at a true 450 with a 366celeron...consider yourself really lucky, cause Intel sets the multiplier at 5.5...time 66MHz FSB, ad you get 366.  To set yours to 450, that meant FSB of 100, times 4.5 multiplier.  Or it could be 83MHz FSB, times the real multiplier of 5.5, but since you said your board only supports 66MHz and 100 MHz FSB, I assume it's the former and not the latter.  In this case, 450 will do good...plus, you could make a pretty penny off that thing if it's truly working at that speed.  The easiest way is to see what it says on the POST screen.  (Power On Self Test).  To answer your questions down the line...
1.  Don't know...but it sounds like you did...possibly a little too far for your CPU, other add-in cards, or memory to handle.
2.  The best settings are always the original settings.  Overclocking will reduce the life of your CPU...unless you can cool the core of it to the same temp as running it at original clockspeed.
3.  Active cooling is always the best.  If you have a slot1 CPU, you can buy an after market cooler that has a clamp, holding the cooler onto the CPU... the cooler will have instructions on how to use it.  If you have the socket370 PPGA version, you can use any socket 7 or socket 370 cooler.  The best ones have really large heatsinks/surface area...more pins and longer pins are better, and a big, loud fan always works best.  Higher cubic feet per minute (CFM) ratings are the best.
4.  Depends on the board.  Some mobos have jumpers or dip switches to adjust voltage, others have a "Soft BIOS" that allows control in the BIOS...others yet, follow the Intel spec and don't allow adjustment at all.  The BX spec requires auto select of both voltage and FSB settings.
5.  The best option is a plain old heatsink and fan.  Peltier coolers are okay, if you want to fry your board.  They create condensation in humid climates.  If you would like to use a Peltier, make sure you apply the TEC properly with proper sealants to prevent condesation, or you'll get "inactive silicon".
6.  Lots of bad things can happen, from CPU meltdown, RAM meltdown, burnout of soundcard, AGP card, modem (due to possible increase of system bus if not using 66 or 100 MHz FSB), system instability, errors, data corruption, possibly even problems with the power supply not able to deliver the increased power...(rare).  If you use this thing for work, best not to overclock.  Last but not least...if you don't already have 100MHz (pc-100) RAM, better get some, or it may cause more problems by being to slow.  Checkout www.arstechnica.com, www.hardocp.com, www.tomshardware.com for some good tips and info on overclocking.  

the reason you could run your computer at the bus speed of 100mhz is because you don't have PC100 compliant memory, if you get this then you will be able to run your motherboard at 100mhz, if you get this kind of ram you will need to get some additional cooling power to run your processor at 500 mhz(plus possibly increaswe your voltage.
question 1.
yes if you are running a processor at a higher speed then what it is rated for (eg 366mhz running at 450mhz) then you have "overclocked" it.(this is what the term overclocking refers too).

question 5.
I would get a good fan for your processor and some kind of additional fan for your case (there is a fan you can get the sits in one of the 5 1/2' drive that will blow cool air into the case)

question 6. your could get data corruption errors but most of all overclocking will reduce the overall life of your cpu.(probably only shorten it by a year so instead of it dying in 3-5 years it will die after 2-4) memory wouldn't be affected nor should hard drive or motherboard because these are not working at accelerated speeds( as long as the cpu is properly cooled you motherboard won't "feel the heat"), your addon cards won't be affected either because your motherbaord supports 100mhz bus and you aren't running it a a weird bus speed like 115mhz or 83mhz.(this would cause stress because of the actual mhz speed they would run at after the 1/3 clock divider got thru with the motherboard speed.) your cpu is the only thing you will see affected because it is the only thing you are "overdriving".

Thanks very much for all your help. I still have some questions to ask. I've just found out that the bus speed can be changed to 75, 85. Would this make any better to the overclock settings? About the cooling fan, I have some kinda metal bit that's above the cpu then the fan. Would I need a new cooling fan? or can I just put in another one and if so how and where in mainboard? Would pc 100 and pc130 ram work on a 66mhz bus? I tried to boot up win98 on a 100mhz bus and i got this msg that said something about xms memory thing. Is this something to do with pc66mhz ram? I've overclocked 366 to around 468 (85mhz x 5.5) and everything worked fine apart from the temperature of the cpu, so how do I know if I need to increase the voltage?
I cannot any jumpers for the voltage and it's not in the bios as well. :( I was running at 468mhz and my agp was going real hot, how do I cool that down? I opened up the case but it didn't help much. One last question how can you tell if the SDRAM is a pc66 or pc100. In my bios set up there's an option for bank DRAM timing and the settings were at SDRAM 8 ns, What's the difference between 8 and 10 ns?
Thanks in advance

thanks for all that :)

one last thing :) I've changed my memory to pc100 and i ran at 100mhz bus, but I still got that xms memory message from windows, sometimes it didn't even boot. What could this be?

hmmm I was pretty sure that the xms error was a memory thing. it could be that the try running at 100mhz bus speed and slowly change the clock multiplier up, it could be that even thought the memory will work at 100mhz the cpu may be maxing out at 450mhz, they are only "so" overclockable.

try it and post your results.

ok I set the jumper to 66mhz bus but i changed it to 100mhz bus in bios. When I reboot, system just went dead. I turned off and on the system and the default bios was loaded.  So I set the jumper to 100mhz bus and the bios settings stayed the same. The system hung when it got to verify dmi pool data.........update success. the bus was at 100mhz and i was running at 550mhz. I changed the multiplier but it didn't change/effect the speed of the cpu. It worked fine on 75 and 83mhz bus. Does this mean that I would need to up the voltage when i'm running on 100mhz bus? or???
and also My video card has gone very hot, eventhough i'm running at the normal configuration. Have I done something wrong when i was changing the settings? or is it suppose to be hot. My video card is sis6326AGP. I can't leave my hand on the heatsink longer than 4 secs. that's how hot it is. Thank you for your help

looks like your clock multiplier is locked at 5.5 (66mhz x 5.5 =363mhz or 5.5 x 100mhz =550) I think that your system is hanging because the cpu cant't handle 550mhz (200 mhz is a big jump).

ok if you set the jumper to 66 or 100 mhz set the bios to the same value. is there a jumper for the multiplier? if so then chage it and the bios settings to the same level. start off slow like only overclock it to 400mhz and then move up from there.

man this discussion could go on for days, 8-) do me a quick(relatively)favor and go to this web page:
http://www5.tomshardware.com/overclock.html

check out the info that is there, a lot of the questions you have will be answered in more detail than I could give(like the fact that you have a 366mhz cpu leads me to believe that it might not support 100mhz bus speed, hopefully not)
after you have perused it feel free to post any more questions and I will still try to help. if you have a problem posting here then e mail me at
somebody@bigger.net
you can get a hold of me that way.
sound cool?
ok man see ya later.