AMD Athlon 64 3200+ Winchester Core - $180
The 3200+ Winchester core will run cooler than the Newcastle core. In addition, the 3200+ can probably reach 3800+ speeds pretty easily for about half the price.
Abit Av8-3rd Eye Motherboard - $139
This is without a doubt the best AGP based socket 939 board out there right now. Abit makes some of the most stable boards availible and this one is no exception. A bit more expensive than other AGP socket 939 boards, but it's well worth it.
OCZ Rev3 Gold Edition Dual Channel Kit 2x512MB - $231.50
I choose this memory because it's a bit cheaper than G.Skill and will fit your budget easier, and increased the speed to PC3700 for ease of overclocking. This means you could easily hit a 233MHz HTT speed, keeping your RAM on a 1:1 ratio, without even touching speeds past stock.
OCZ Powerstream 520 watt power supply - $140
Many people put a lot less consideration into the power supply than they should, considering it's the part which powers the rest of your system. This power supply has rock solid rails, and it actually allows you adjust them to suit your needs. It also has indicators on the back which will inform you of over or under powered rails. Once you start putting expensive, high end parts in your machine (which you are), you need a good PSU to run them with.
Total - $690
Your case is really just personal preference, it's not really too important, you just want a pretty sturdy frame, and good airflow.
Your hard drive will be a SATA hard drive, as it's faster than the regular ATA-133. The size is really up to you, 120GB drives are dirt cheap right now though if you are looking for a good catch. Seagate and Western Digital are the better hard drive manafacturers so that's what you'll want.
Throw in a Thermaltake Venus 12 Heatsink with some arctic silver 5 thermal paste, and you may want to consider an aftermarket heatsink for your video card. Other than that, you're set.
And keep your money mate.