AMD Athlon 1.2Ghz, Retail w/heatsink & fan 150 newegg.com
Antex Performance series, 100-145 depending, techstore.com
Iwill KK266 for SDRAM solution, 120 newegg.com
Matrox G450 for 2D or Radeon 64MB for 2D and 3D, both at newegg.com 95 or 160 depending
256MB RAM from crucial.com @ 60
Turtle Beach Santa Cruz @ 70 or Hercules GTXP for 140 if you want more options and versatility
IBM 60GB 60GXP for 180 @ newegg.com
This is just one of many different paths you can take. More info is needed for more specifics, like Athlon or Intel? DDR or SDRAM? High performance sound? Video? How much storage? Want RAID?