Should we buy gigabit switches over fast ethernet?

  Your network design is very dependent on what you intend to do, and what your budget is.

  People have bragged to me that they've set up their home at GigE speeds.  That's usually two or three PC's, and a residential uplink (20Mb/s max).  If you can't possibly do over 20Mb/s, why do you think you need more than 20Mb/s (100Mb/s switch)?

  A similar conversation came up about what wireless networking to support.  This person had a 2Mb/s uplink.  They wanted to migrate all of their stuff up to 802.11g.  There's no harm in it, but it won't help their speed.

  MRTG is fairly simple to install and configure.  Use it to monitor your port speeds.  Most people want to upgrade when they reach 60% to 80% utilization.  

  One guy insisted that his server NEEDED GigE.  When I showed him his graphs he realized that he was content on 10/100.  His peak bandwidth was about 40Mb/s during file transfers, and his normal bandwidth was only about 2Mb/s.  Why waste a GigE port on something so low?  The limitation was his application, not the available bandwidth.

  I'm very fond of Cisco equipment.  I've had problems with the Dell switches in the past.  They simply aren't as fast nor reliable in high load environments.   If you're not in an extremely high load environment, then it's not as big of a concern.  I've known people with HP equipment in the past, who upgraded to Cisco when they could.  They're good, but if you're in a really high load environment, you'll want to upgrade to the best.

  You may wish to consider upgrading to something better than a standard 24/48 port switch.   A year or so ago, I upgraded my office from a collection of 24 port switches to a Catalyst 5500 13 slot chassis.  That's 2 supervisors (what runs it), and 11 slots for line cards.  It's populated with 6 24 port 10/100 line cards, and 2 48 port 10Mb/s cards.   In the last year, no one has really touched the switch.  I demonstrated the hot swap capability of the power supplies (shut one down, pulled it out, put it back in and powered it back up), and added the second supervisor.  It hasn't had a need to be shut down or power cycled since we brought it up.  I did add the redundant supervisor, but no restart is required.  We've added ports, and I've done some tracing of MAC addresses (who has this MAC?), but that's normal operation. :)

  Here's a picture, before we swapped the top line card for a supervisor.

http://jwsmythe.com/ebay/Cisco_5500_13_slot_2.jpg

  The 10 Mb/s ports had been intended to be VoIP, but later a vendor was selected and they provided 48 port 10/100+POE switches, and didn't want to run on our hardware.  They wanted to make the extra buck selling us switches.

  For the upgrade capability, you should consider a 6000/6500 chassis.   There's a whole variety of line cards available, and you can upgrade on the fly.  Simply put a better line card in a slot, move the connections to the new card, and you can pull the old card out to free up a slot.  

  You can get an used 6000/6500 chassis pretty cheap on eBay.  You can also get the line cards very cheap also.  You probably don't need the latest greatest and most feature filled cards, so people are selling their old cards cheap.   I don't have my spreadsheets with me, but if my memory serves me correctly, I estimated at median eBay prices that I could build a nicely populated 6500 chassis out for about $2000.   That was to meet our needs.  Yours will likely be a lot cheaper.

  All in all, this would give you a huge port density so you won't have to manage multiple switches, a brand that's extremely reliable (there's a reason virtually every provider uses them), and the flexibility to upgrade as your business requires, without replacing entire switches.   It's always cool to show customers the enterprise switch that you run in your wiring closet too. :)   It looks a lot better than someone seeing a bunch of small switches with crossovers stacked on top of each other.

  If you find there is a requirement for one or some users to be on GigE, put them on the GigE card.  You'll always find a few "power" users who scream that they MUST have GigE.  Put them on the GigE card, and let them go.   They'll be satisfied.

  It'll be a few days before I'm back to my office.  If you're interested, I can post some of the part numbers and median prices, so you can estimate your needs.  

  I'm a big fan of buying from eBay.   I've configured several chassis switches like this from parts acquired there.  I have a few 5000 cards at my house still from customers who wanted changes before I installed the chassis, or from upgrades.  I had less than a 10% failure rate in buying from eBay.  Where the parts are so cheap compared to new, it doesn't hurt.   Be careful who you buy from.  Check the descriptions carefully, and carefully track who you got which parts from.  I messed that up when I received about 20 of those 24 port line cards from about 15 different suppliers.  I unboxed them all and then began testing.  2 were bad, and I have no clue where they came from.  I lost about $60 in defective parts that I couldn't return, but made over $1000 selling the complete switches.

  Oh, and to clarify, I'm not offering to build it or consult for you.  I'm busy right now, with barely enough time to hop in here and post.  I'm more than happy to guide you in the right direction so you can do it yourself.  :)

  If you really want standalone switches, you should look at the Cisco Catalyst WS-C2960G-48TC-L .  I have a different spreadsheet back at the office that has the comparison of Cisco gear for PPS and backplane fiber throughput.  The 2960's are pretty good switches.  I know of one place that has a dozen or so deployed with absolutely no problems.  They're afraid of going to a big chassis, so they continue with the collection of standalone switches.

  Switching to Cisco, you may see a performance increase over other switches.  It'll really depend on your load.  I went from a hub to a WS-C2980G-A (80 port 10/100 with GBIC uplinks).  I do have a 20Mb/s uplink, but I see absolutely no difference, because the most I'll ever do is 20Mb/s.   I only really needed about 5 ports, but I bought a lot of them and haven't sold all of them yet. :)

No you do not need stacking at all. You benefit from it if you want to make the two switches act as one for simplified management. No network traffic crosses the stack cables. You can simply uplink your switches.