Well the Athlon 64 3200+ is solid and quite powerful and OCable, and cheaper than the weaker Athlon 64 3000+ on Newegg.com
Any memory will do if your not planning on Ocing, just make sure it's PC3200 and runs in dual channel with decent timings and your all set.
As for video card, your main options are 6600GT, 6800GS, 7800GT and 7800GTX. The 7800GT is probably one of the better options, although the 6800GS is great too. All four provide good performance and bang for buck (excluding the 7800GTX).