What exactly will the server be doing? If it's more or less just a file server, a fast CPU isn't as important as the hard drives and memory.
Going with what Anti-Trend has said, $400 to do a PC with RAID is going to be really tough. While 60GB drives are available, I found 80GB SATA drives for less than $2 more than a 60GB, so for the money, that's really what I'd stick with.
Motherboard: MSI KT6V-LSR, KT600 w LAN, SATA RAID -- $55.00
CPU: Athlon XP2600 Retail (includes CPU heatsink, warranty from AMD) -- $97.00
RAM: Kingston Value Series 512MB PC3200 --$79.00
Hard Drives: Seagate 80GB, 8MB cache x2 ($72.75 ea.) -- $145.50
CD-ROM: Samsung 52x CD-ROM --$15.99
Floppy drive: NEC 1.44MB Floppy drive (you'll likely need it to provide SATA drivers for the OS during installation) -- $8.00
Case w Power supply: Antec SLK3700AMB w 350W power supply (Antec SL350S): --$65.00
Total: $465.49 + Tax (if in CA or NJ) + Shipping
All prices from
Newegg.
A cheap video card, if you decide you actually do need one, can be had for less than $20 if you do need display capabilities.
If you'll be doing a remote install, you could drop the CD-ROM out, but I believe that you may still need to have the floppy.
For stability reasons, I would avoid anything from Epox for motherboards. They are about the only brand, other than PCChips/Matsonic, that I advocate avoiding like the plague. Stick with Antec or Sparkle (also Fortron) power supplies. At the very least, have a 300W power supply, but I'd stick with 350W or better, just to be on the safe side.