Haaa ! I've been waiting for this question ! Here's a configuration for around 2000 bucks
You need...
1. Mainboard : Socket 754 or 939/940
2. CPU : A corresponding one for the socket ( athlon 64 on Socket 754 and Athlon FX on 939/940
3. Case : CS-901 is my recommendation , well equipped with fan sockets

4. Graphics Card : X800 XT or 6800 Ultra , take what you want !
5. Hard disc : I prefer Seagate , they're unhearable .
6. Drive : A Plextor DVD-Burner , you can't do anything wrong with plextor !
7. Power supply : at least 450 Watts !
That explanation isn't very exact , ask somebody else for exact recomendations , i'm not that experienced with the Athlon 64-generation CPU's .