Here are some ideas
AMD Athlon 64 x2 6000+ 3.0Ghz
http://www.newegg.com/Product/Produc...82E16819103773
MSI K9N SLI Platinum Socket AM2 NVIDIA nForce 570 SLI MCP ATX AMD Motherboard
http://www.newegg.com/Product/Produc...82E16813130048
Western Digital Caviar SE WD3200JS 320GB 7200 RPM 8MB Cache SATA 3.0Gb/s Hard Drive - OEM
http://www.newegg.com/Product/Produc...82E16822136017
nMEDIAPC HTPC 500BA Black Aluminum Panel/ 0.8 mm SECC body ATX Media Center Computer Case
http://www.newegg.com/Product/Produc...82E16811204023
CORSAIR ValueSelect 1GB (2 x 512MB) 240-Pin DDR2 SDRAM DDR2 533 (PC2 4200) Dual Channel Kit Desktop Memory
http://www.newegg.com/Product/Produc...82E16820145526
COOLER MASTER eXtreme Power RP-550-PCAR ATX from factor 12V V2.01 550W Power Supply 90-132V/180-264V Nemko, TUV, cUL, CE, BSM, FCC, CCC - Retail
http://www.newegg.com/Product/Produc...82E16817171016
ASUS Black 16X DVD-ROM 48X CD-ROM SATA DVD-ROM Drive Model DVD-E616A3T
http://www.newegg.com/Product/Produc...82E16827135143
Creative Sound Blaster X-Fi Xtreme Audio 7.1 Channels 24-bit 96KHz PCI Interface Sound Card
http://www.newegg.com/Product/Produc...82E16829102007
XFX PVT84JUDD3 GeForce 8600GT 256MB 128-bit GDDR3 PCI Express x16 Video Card
http://www.newegg.com/Product/Produc...82E16814150229
ViewSonic Optiquest Series Q22wb Black 22" 5ms DVI Widescreen LCD Monitor 300 cd/m2 900:1
http://www.newegg.com/Product/Produc...82E16824116076
Creative Inspire P7800 90 Watts 7.1 Speaker - Retail
http://www.newegg.com/Product/Produc...82E16836116153
Microsoft CA9-00001 Black 103 Normal Keys 3 Function Keys PS/2 Standard Basic Keyboard and Mouse Included - OEM
http://www.newegg.com/Product/Produc...82E16823109132
That seems to be pretty good for what your looking for. I got to go to bed, but take a look at this stuff. Pretty good.
Oh you may want to add another hard drive, or 1GB of RAM.
Good Luck