Stick with Intel.
SCSI Harddrive is the first thing you need. IDEs, ATAs or SATAs can't multi file chase, that way servers only use SCSI drives.
My server is a dual PIII 1.0GHz, 1 Gig PC133 memory and an UltraWide SCSI. I primarily use it for my file server, as well as, a game server.
The biggest money saver on a server is the video card and sound card. No sound card is required and shouldn't be used. And get the cheapest video card on the market. You are not running games on it, so you don't need it. Plus the monitor is off much of the time anyway.
In order of importance for a server:
-Hardrive - SCSI, Ultra 160 or Ultra 320. UltraWide is good.
-Processor - Intel is a server chip, AMD is not. AMD is more for multimedia events. There are no multimedia in a server.
-Memory - lots of it. Start with 1 Gig and go up from there.
-Network card - good quality over cheap price. 10/100 is great.
-Server Software - Windows Server is easy to use, Linux is free. Both are great.
-Case - good size case...nothing to tight. Don't worry about extra fans, stock fans are more then you need (unless you are overclocking).
-Video Card - cheap is good. You don't use the video for anything other then monitor software.
-No sound - Sound is not needed and it takes up resourses to have it in your system.
And finally...a strong internet connection with awesome upspeed. Most home broadbands are VERY limited on the up speed. Check with your carrier. Don't forget about a file backup plan.
Hope this helps.
Soyo Dragon Ultra Platinum Edition powered by a P4 3.06GHz w/HT @ 533FSB
ATI Radeon X800Pro 256DDR <---Yeah!!! I finally got it!!!
1024MB PC3200, Creative Audigy LS, 2 x 40GB = 80GB RAID 0
Windows XP Pro, DOOM 3, CS, UT2004, BF1942 RtoR, CNC Generals
Finished Half-Life 2!!!!!!!!!!