since your going to drop a nice 1500 on a system, i would assume you would like it to last you a while. Personally i like to keep lower prices and stay behind the curve and buy stuff only when it is needed. But this seems to be the time that everyone is getting ready for 64 bit windows (also known as "Furure proofing"). 1500 can get you a lot, and AMD is the best choice for gaming. Then again, most agree pentium is better for normal applications. My opinion is to go w/ an athlon because they usually have a better price/performance ratio (and you always want that extra performance in games, and AMD's arent bad at all in normal applications, they are good as opposed to great). It all depends on what you are looking for.
Heres my proposed system:
Processor: Athlon 64 3500+ (winchester)
This processor is starting to become one of the best price/performance ratio processors out there. It is overclockable if you so want, and performs extremely well in pretty much any task. The winchester core is 40 bucks more than the newcastle, but is just a much better core (i think its worth the cash now if your buyin a 3500 than having to upgrade sooner than you want). Also, this is socket 939, which is THE "future" in most's opinions. This socket should keep you goin for at least 3 years or more.
Heatsink/Fan: Any of these are good for socket 939
Motherboard: MSI "KN8 Neo4 Platinum SLI"
You do not really NEED SLI to perform well, but again with 1500 you can prepare for the future (if you dont know, SLI is where you can run 2 GFX cards at once). Games now havnt even touched the surface of 2 high end GFX cards, and the limiting factor becaome the CPU with SLI. If you would like, i posted a link to a 2nd Motherboard that does not have it, but it was the most popular 939 board on newegg before SLI came out.
Power Supply: Thermaltake SilentPurePower 480watt
Ever since i got this psu for christmas, ive been raving on how well it works. This think blows a lot of air out of your case w/ the 2 fans and isnt loud. 480 watts should be enough for whatever you are doing. Thermaltake is a well known company for anything they make so reliability isnt too much of a problem. Also, this link is a black version, and it comes in a few other colors if you want to match your case (look around). What can i say, its a great PSU.
RAM: Corsair 1 gig (512x2)
You are correct in saying 2x512 is better, though by only a bit. I check up and found the 2 cheapest options. You can go corsair value ram which is great, but not as overclockable if thats where you want to go (about $140). Then there is the Corsair XMS extreme if you want to overclock (about 180). Depends on what you want. I posted both (btw, 1 gig should work fine):
According to my calculations (estimate in my head, with the SLI board), this should leave you with around 800 for the video card(s). If you are looking for a card that will play anything for now, but not at the highest settings, go for the 6600gt. Great card great performance, and will cost around 200. EVGA is a good reliable brand that puts good fans on thier cards:
If you are looking for a bit more performance you have 2 choices:
-you can use an SLI board and use 2 6600GTs in SLI
-get a 6800GT
Now i am not sure of the difference between the 2 performance wise, but remember that in the future, if you want to upgrade from 2 6600GT's you have to get rid of both cards, where as from one 6800GT you can just add another and increase performance by over 50%. Either way you are looking at a 400 price for the 2 6600GT's and 450 for a 6800GT PCI-E version (out of stock at the moment, but the EVGA version is in for 500).
6800GT PCI-E: http://www.newegg.com/app/ViewProduc...150-081&depa=1
Now all these options are your choice of which way to go, and i know ther is a chance that you could disregard all my options, but im just here giving suggestions so its ok. Especially deciding for video cards. See how much you are willing to spend and look at when you are wanting to upgrade and such. If you feel no need for SLI, then dont get it and go for a 6600GT or a 6800GT. If you are interested in SLI, i would go for the 6800GT, simply because it will be easily upgraded by just adding another one in the future. 2 6800 GT right now are limited my the CPU so i dont see them being obsolete any time soon.
I also suggest picking up a few extra things as extra case fan and themal paste (arctic silver 5) to keep that CPU cool.
good luck and id be happy to answer any questions you got
(lol im turning into nubius... this took some time)