if you want to get god parts for a good price, use places like newegg for your stuff. DON'T EVER USE EBAY.you'll get scammed. kijiji is also ok. you could buy from retail stores, but they'll eat up your budget with all those taxes faster than a gas guzzler that's low on fuel.
here's my suggestion....
-graphics card at least an ATI hd5770 or an nvidia GTX260. Crossfire OR SLI will really boost your performance, but may give you issues later on.
-quad-core CPU. those are pretty cheap now. either the Core I7 or I5 quad-core is good.
- at least 4gb ram. the more, the merrier. try to buy the faster ram.
-at lease one 1 terabyte hard drive to store all those files
-a really good case with excellent airflow. I'd suggest the antec 1200 because of it's giant 200mm fan on top. it also glows blue*it looks epic*
-1 or 2 SATA DVD-RW drives or possibly a blu-ray drive.
- a really good aftermarket cooler.stock market cooler suck. you clould buy the coolermaster V8.
-and a power supply that's at least 600 watts and has SLI/Crossfire support if you're going to use CF/SLI. i prefer a power supply made by OCZ
-and other accessories like thermal paste, fans(try to make them silent),CARD READER, and other stuff like that.
-and the most important part, the motherboard. first you choose your CPU, figure out what type of socket it has and then you choose the motherboard. make sure the type of ram you buy is supported by the board. my favorite maker is ASUS. they have good product quality 95% of the time.
you could also get 2 monitors if you have enough left over.