Okay I'm making a set up and will explain why it's good, will edit in a few minutes..
Processor:
I believe you said you'd be overclocking, so like others have said, the Opteron 170 would probably be your best bet. It overclocks like a beast, period.
http://www.newegg.com/Product/Product.asp?Item=N82E16819103586
Motherboard:
Going along with the overclocking scheme, the DFI Lanparty UT Motherboard is fantastic for overclocking. Watch out for the expert boards though, they're known for having some problems.
http://www.newegg.com/Product/Product.asp?Item=N82E16813136152
Video Card:
With your budget, it's not hard to see you want to get the most out of your system, and since the 7800GTX 512mb is currently the best video card out, it'll be able to show you put a lot into your computer. It's able to play any game out right now and will continue to for a very long time.
http://www.newegg.com/Product/Product.asp?Item=N82E16814143044
Power Supply:
Yes the Antec and OCZ power supplies are nice, but PC Power & Cooling has an awesome powersupply out, with 650W peak power and 510W Constant. It's very well made and reliable, you wont be dissatisfied.
http://www.newegg.com/Product/Product.asp?Item=N82E16817703001
RAM - Well it's a definate that you will want 2Gigs of RAM, but which kind is best for overclocking? Well, it's my honest opinion that this OCZ ram is the best bang for the buck ram out there. This ram can overclock like crazy, have fun.
http://www.newegg.com/Product/Product.asp?Item=N82E16820227210
Hard Drive - Well I would have suggested some Raptors, but I thought in your case you may prefer space to speed of performance. If not, you can easily get a raptor as a side hard drive or something, but if not, these 250Gig Seagates will do you nicely.
http://www.newegg.com/Product/Product.asp?Item=N82E16822148065
Case - Thermaltake XASER, a very well built case with nice airflow and room, it also is very durable.
http://www.newegg.com/Product/Product.asp?Item=N82E16811133154
Soundcard - The Creative Soundblaster X-FI is definately the best for the money. It delivers amazing sound with advanced eax support, bringing you crazy nice, crisp sound.
http://www.newegg.com/Product/Product.asp?Item=N82E16829102188
Optical Drives - Don't really matter much, just maybe get two along these lines:
http://www.newegg.com/Product/Product.asp?Item=N82E16827106013
and
http://www.newegg.com/Product/Product.asp?Item=N82E16827101668
CPU Cooler - The Zalman 120mm fan is amazing for overclocking, being very reliable and durable.
http://www.newegg.com/Product/Product.asp?Item=N82E16835118115
This'll bring you close to your budget, but you still have some room. Need a keyboard or mouse, maybe some speakers?
Mouse:
http://www.newegg.com/Product/Product.asp?Item=N82E16826104191
Keyboard:
http://www.newegg.com/Product/Product.asp?Item=N82E16823175103
Speakers:
http://www.newegg.com/Product/Product.asp?Item=N82E16836121118
You'll have a monster of a system.