If I remember correctly, the Radeon 9550 is spec'd higher than the FX5200. The FX5 series and the Radeon 9 series are in the same generation too. The FX5200 is a low-end card and the Radeon 9550 is a mid-range card. I am 99.999% sure that the Radeon 9550 will blow the FX5200 away.
I have the FX5200 in a very old system and it really sucks for everything. Unless you know how to overvolt/overclock it and put a bigger heatsink on it, there really is no reason to go with the 5200. Get the 9550.
ive owned a 9550 for about 2 years now and its still running fine. I have 2 computers and one is for older games running with the 9550. It runs like champ and im not going to upgrade it any time soon.