The only "XPs" now are Socket A Semprons. However, they are not good for new generation gaming nor do they provide any great speeds. Your choice these days are the Semprons for socket 754 if yer thinking budget, Socket 754 A64s if you want something a bit better but more expensive and Athlon 64s for socket 939 for the new systems. The Athlon 64s in all its flavours should do fine with gaming. The best choice would be the newest X2s or even better, the FX53 or the FX55 (possibly even FX57).
JAN