Connecting ATA/100 HDD to an UltraATA/66 Controller

I have an HP Vectra VL400 733MHz computer.
It supports only UltraATA/66.
I want to purchase a new HDD, but as I saw, in most of the stores, there aren't any ATA/66 HDDs anymore, only ATA/100 and better.
The question is - will the ATA/100 HDD work on my motherboard with the ATA/66 controller (with ATA/66 speed of course), or will it not even be detected?

I know that plugging ATA/66 HDD to ATA/100 Controller WILL work since it is backwards compatible, but does it work the other way around?

Googling didn't help me much...

Thank you very much!

(also asked in Storage area:
Boris AranovichSenior Software EngineerAsked:
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zvitamConnect With a Mentor ConsultantCommented:
Most Plug-in IDE controller present themselves as SCSI controllers to the BIOS, and therefore not necessarily need drivers in order to function.
crazijoeConnect With a Mentor Commented:
Yes you shouldn't have any problems connecting a ATA/100 HD to a ATA/66 controller. It will only perform at ATA/66 specs.
Agree with crazijoe, both the IDE interface and the drives are backwards compatible so you can use any combination of drive/ide controller and they will work together.
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I do agree you should have no problem with the ATA/100 drive on your system. You could add a PCI card if you want to use the full speed of the hard drive though.
Anyway, the fact that the system is ATA/66 compatible, means that it's few years old, and the BIOS might not be compatible with the new disks because of the size of the disks not the ATA standard.

if that the case consider upgrading your BIOS, or buy a plug-in PCI-IDE controller like those produced by promise for example

(and then enjoy ATA/100 or even ATA/150 (serial) speed)
Boris AranovichSenior Software EngineerAuthor Commented:
PCI Cards for ATA Controllers - what about the BIOS? The BIOS will not detect those HDD's, on an PCI controller, right? They only will work under the OS with the correct drivers?
Just a suggestions, with a 733 mhz machine ur not gonna notice much of a difference with a faster IDE ur money for a new machine :)
Boris AranovichSenior Software EngineerAuthor Commented:
haha :D I know I know

Actually, 733 isn't that bad, this is a pretty strong and stable CPU... I am upgrading RAM and HDD and etc., to make it work fluently :)
Boris AranovichSenior Software EngineerAuthor Commented:
thanks for all the help :)
even though crazijoe's answer is the direct answer that I needed, I accepted his answer already for this question in the "Storage" area, so here I put him as assist, and zvitam - you got the points for the 2nd part of the question and help :)
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