You didn't mention if you needed an OS or not. Usually prices for systems are by default
hardware only and that's how this is set up. If an OS needs to be included with the $800 limit tell me and we can adjust a few things.
AMD:
AMD Athlon 64 X2 3800+ Windsor 2000MHz HT Socket AM2 Dual Core Processor Model ADA3800IAA5CU -:
http://www.newegg.co...N82E16819103735BIOSTAR TFORCE4 AM2 Socket AM2 NVIDIA nForce4 ATX RoHs compliant:
http://www.newegg.co...N82E16813138028FSP Group (Fortron Source) AX400-PN, RoHS, 12cm FAN, version 2.0, 2 SATA, 20+ 4 pin, PCI Express, 400W:
http://www.newegg.co...N82E16817104953OCZ Gold Series 2GB (2 x 1GB) 240-Pin DDR2 SDRAM Unbuffered DDR2 667: (has $40 rebate)
http://www.newegg.co...N82E16820227078SAPPHIRE 100154 Radeon X1800XT 256MB 256-bit GDDR3 VIVO PCI Express x16 Video Card:
http://www.newegg.co...N82E16814102007COOLER MASTER Centurion 5 CAC-T05-UW Black Aluminum Bezel, SECC Chassis ATX Mid Tower Computer Case:
http://www.newegg.co...N82E16811119068$779.91 shipped. 739.71 after mail in rebate
Very solid build. The 7900GT would be a better choice, and can be squeezed in and still be under budget. However it's hard to recommend them because of large amounts of faulty 7900GT cards. If you want to take a chance, it would be better than the otherwise hot/noisy x1800XT. An x1900xt may be a little too much over budget but also a good choice expecially for gaming.
Intel:
Core 2 Duo E6300:
http://www.zipzoomfl...oductCode=80858Gigabyte GA-965P-DS3 Socket T (LGA 775) Intel P965 Express:
http://www.newegg.co...N82E16813128012OCZ Gold Series 2GB (2 x 1GB) 240-Pin DDR2 SDRAM Unbuffered DDR2 667: (has $40 rebate)
http://www.newegg.co...N82E16820227078FSP Group (Fortron Source) AX400-PN, RoHS, 12cm FAN, version 2.0, 2 SATA, 20+ 4 pin, PCI Express, 400W:
http://www.newegg.co...N82E16817104953SAPPHIRE 100154 Radeon X1800XT 256MB GDDR3 PCI Express x16 Video Card:
http://www.newegg.co...82E16814102007RCOOLER MASTER Centurion 5 CAC-T05-UW Black Aluminum Bezel, SECC Chassis ATX Mid Tower Computer Case:
http://www.newegg.co...N82E16811119068$871.91 shipped, $831.91 after MIR
Intel's a bit hard to recommend for right now. Core 2 Duo is just now coming out, and prices seem a little bloated and out of stock in many places. The C2D compatible motherboards have just started rolling out as well, and have similair troubles. As you can see, to come closer to the price range there is an open box X1800XT. Shouldn't matter as Newegg still gives a warranty (however it's pretty short, but enough to see if it's working well or not.)
Sorry for going that far over budget, but in a few weeks there should be better prices for Core 2 Duo CPUs and motherboards.
You could get a great Pentium D system... even with an x1900XT. But I don't think anyone really WANTS a Pentium D system now that Conroe has been released XD. for kicks, here's Pentium D Intel:
Intel Pentium D 805 Smithfield 533MHz FSB 2 x 1MB L2 Cache LGA 775 Dual Core,EM64T Processor
http://www.newegg.co...N82E16819116001ASUS P5ND2-SLI Socket T (LGA 775) NVIDIA nForce 4 SLI
http://www.newegg.co...N82E16813131578OCZ Gold Series 2GB (2 x 1GB) 240-Pin DDR2 SDRAM Unbuffered DDR2 667: (has $40 rebate)
http://www.newegg.co...N82E16820227078SAPPHIRE 100149L Radeon X1900XT 512MB 256-bit GDDR3 VIVO
http://www.newegg.co...N82E16814102025FSP Group (Fortron Source) AX450-PN, 12cm FAN, version 2.0, 2 SATA, PCI Express, 450W
http://www.newegg.co...N82E16817104954COOLER MASTER Centurion 5 CAC-T05-UW Black Aluminum Bezel, SECC Chassis ATX Mid Tower Computer Case:
http://www.newegg.co...N82E16811119068$859.41 Shipped. $819.41 after MIR
The non-C2D motherboard are much cheaper right now. The 805 is only $104 and is a great overclocker. It's 2.66Ghz stock but can be pushed to 4.2Ghz with Watercooling, with a good air cooler it can hit some good clocks as well. Not sure how high it can go with the stock cooler, but ishould be pretty good. Those two reasons are why you can get an X1900XT within your price range, which really matters the most in gaming...
All good systems. It wouldn't be a bad idea to wait for C2D CPUs + motherboard prices/selection/availability to solidify. Also DirectX10 is coming, we don't know when exactly when but it might be worth it to wait a couple months if you don't need the system right away. However... personally I hate waiting because if you're always waiting for the next best thing for computers... you'll be waiting forever.