Most of these builds are from my own collection, though I've included some third-party parts; I'll note the origin where applicable. 😉
Gaming Rig ~ $1167
Intel (LGA 775)
1 x Gigabyte EP35-DS3 V2.1, lga 775, intel P35+ICH9, FSB 1600 O.C./1333
1 x Intel Pentium Dual-Core E5200 Processor, 2.5GHz, socket 775, 2Mb cache
2 x Kingmax 2GB (2048Mb) DDR2 PC6400, 800MHz, CL5
1 x Gigabyte Radeon HD 4670 512MB DDR3, 128bit, DVI-I / D-sub / HDMI
1 x SAMSUNG 320GB HDD, 7200rpm, 16MB cache, SATA II-300, F1, HD32
1 x CORSAIR 400W Power Supply, CX Series CMPSU-400CXEU, 12cm fan
1 x LG GH22NS DVD Writer, DVD±RW, 22x DVD±R, 8x DL, 40x CD-R
1 x Chieftec CG-01B-B Case, black, USB, eSATA, 440mm x 180mm x 460mm
$1128
AMD
1 x ASUS M3A78 Motherboard, AM2, AM2+, AMD 770, SB700, 5200 MHz Bus, DDR2
2 x Kingmax 2GB (2048Mb) DDR2 PC6400, 800MHz, CL5
1 x Gigabyte Radeon HD 4670 512MB DDR3, 128bit, DVI-I / D-sub / HDMI
1 x SAMSUNG 320GB HDD, 7200rpm, 16MB cache, SATA II-300, F1, HD32
1 x CORSAIR 400W Power Supply, CX Series CMPSU-400CXEU, 12cm fan
1 x LG GH22NS DVD Writer, DVD±RW, 22x DVD±R, 8x DL, 40x CD-R
1 x Chieftec CG-01B-B Case, black, USB, eSATA, 440mm x 180mm x 460mm
1 x AMD Phenom II X3 710 Processor, AM3 socket, BOX, 7.5Mb cache
$1216
Gaming Rig ~ $1667
Intel (LGA 775)
1 x Gigabyte EP45-DS3, lga 775, intel P45+ICH10, FSB 1600OC
1 x Intel Core 2 Duo E8400 Processor, 3GHz, socket 775, 6Mb cache
2 x Kingmax 2GB (2048Mb) DDR2 PC6400, 800MHz, CL5
1 x Zalman Gigabyte Radeon HD 4850 512MB DDR3, 256bit, DVI-I
1 x SAMSUNG 500GB HDD, 7200rpm, 16MB cache, SATA II-300, F1, HD50
1 x LG GH22NS DVD Writer, DVD±RW, 22x DVD±R, 8x DL, 40x CD-R
1 x Chieftec CG-01B-B Case, black, USB, eSATA, 440mm x 180mm x 460mm
1 x CORSAIR 400W Power Supply, CX Series, 12cm fan, ATX2
$1681
AMD
1 x AMD Phenom II X4 920 Processor, AM2+ socket, BOX, 8Mb cache
1 x ASUS M3A78 Motherboard, AM2, AM2+, AMD 770, SB700, 5200 MHz Bus, DDR2
2 x Kingmax 2GB (2048Mb) DDR2 PC6400, 800MHz, CL5
1 x Zalman Gigabyte Radeon HD 4850 512MB DDR3, 256bit, DVI-I
1 x SAMSUNG 500GB HDD, 7200rpm, 16MB cache, SATA II-300, F1, HD50
1 x CORSAIR 400W Power Supply, CX Series, 12cm fan, ATX2
1 x LG GH22NS DVD Writer, DVD±RW, 22x DVD±R, 8x DL, 40x CD-R
1 x Chieftec CG-01B-B Case, black, USB, eSATA, 440mm x 180mm x 460mm
$1680
Gaming Rig ~ $2000
Intel (LGA 775)
1 x Gigabyte EP45-DS3, lga 775, intel P45+ICH10, FSB 1600OC
1 x Intel Core 2 Duo E8500 Processor, 3.16GHz, socket 775, 6Mb cache
2 x Kingmax 2GB (2048Mb) DDR2 PC6400, 800MHz, CL5
1 x Sapphire HD 4870, 512Mb GDDR5, 256bit, upgraded BIOS! Includes heat pipe!
1 x SAMSUNG SpinPoint F1 750GB HDD, 7200rpm, 32MB cache, SATA II
1 x LG GH22NS DVD Writer, DVD±RW, 22x DVD±R, 8x DL, 40x CD-R
1 x CORSAIR 400W Power Supply, CX Series, 12cm fan, ATX2
1 x Coolermaster CM 690 Case, black, 213x482x524.5mm (W/H/D), with I/O panel
$1944
AMD
1 x AMD Phenom II X4 940 Black Edition Processor, AM2+ socket, BOX
1 x ASUS M3A78 Motherboard, AM2, AM2+, AMD 770, SB700, 5200 MHz Bus, DDR2
2 x Kingmax 2GB (2048Mb) DDR2 PC6400, 800MHz, CL5
1 x Sapphire HD 4870, 512Mb GDDR5, 256bit, upgraded BIOS! Includes heat pipe!
1 x SAMSUNG SpinPoint F1 750GB HDD, 7200rpm, 32MB cache, SATA II
1 x CORSAIR 400W Power Supply, CX Series CMPSU-450VXEU, 12cm fan, ATX2
1 x LG GH22NS DVD Writer, DVD±RW, 40x CD-R
1 x Coolermaster CM 690 Case, black, 213x482x524.5mm (W/H/D), with I/O panel
$1976