My 5200FX that I currently have is a POS. Its a HUGE HUGE HUGE bottleneck to the rest my my system. If it bottlenecks my 3200, imagine the bottleneck on the 3700...ouch.
The dude NEEDS to change the vid card if he wants to be called a gamer by any stretch of the imagination. The FX 5200 isn't even shown on the lowest benhmarks anymore.
Least least least he should get is the 6600GT (~$150 USD) but for a good system he should go for the 6800GT (~300 USD).
If he doesn't switch out the video card, tell him to forget about the rest of his sytem.
For the processor, 3700+ (~$300?? USD) . Its 2.4 Ghz and with a minor .4 Ghz overclock to 2.8, he can make it perform like the best processor AMD has to offer (~$1100 USD).
Because he SHOULD be switching out the video card, he should get a ass-kicking PCIexpress x 16 motherboard. I suggest one of the high-class DFI Lanparty motherboards. That with a 3700+ will be a lethal combination.
Also, for overclocking, tell him not to get value RAM, Get G.Skill RAM if possible, if not, go for PQI or OCZ. Patriot XBL RAM is perfect for the .4Ghz overclock he should do.
MOST OF ALL, GET RID OF THAT POS VIDEO CARD. I can call it a POS because I currently use it myself -.- With my system, I can only play BF2 at the bottom lowest settings because of it. If he doesn't, tell him to screw the rest of his new system.