Personally I'm a reformed Intel Guy. My first and 2nd CPU's were INTEL and they just got blown away by the AMD that I purchased after that and have stayed since with.
My current Server Configuration is a Single CPU server unit.
AMD 2100XP
1 Gig PC2700 DDR
ASUS A7V333 Raid Mobo
20gig & 80gig HD's (The 20 stores the accounts, the 80 stores the gaming files)
both HD's running at UDMA 100 both drives are also 7200 RPM spindle which does make a diff over the standard 5k series drives
My server max at this time is only 15, my players don't complain about lag ever being much of an issue until too many modders create memory lag. I used to run at 25 on only a 300kbps upstream DSL connection. Now I am on digital cable, but my upstream is capped to only about 225kbps.
I'd like to point out again since I know I've said this before on a CPU thread several months ago. It does not matter what CPU you use, as there are only 2 companies that make them. Your server's capacity will be affected by system ram available, ram installed, and your bandwidth upstream. CPU helps a little, but one has to wonder how one such as myself is running 2.5 year old tech, and I'm having no lag or very little-moderate during cheaters run of the server.
And there is one thing right in Joe's post above, don't go by internet posted results, and definitely don't go by the manufacturers results of their CPU's because depending on the server setup will depend on how well your machine will or won't do.
Skyevalen - Admin/Server Op
Hunters Association
http://www.sccommand.com/hunters/