Ok, now google AMD athlon 64 X2 Dual core 4200 windsor see if you can find tech specs, it will tell you what it suits,
Cpu-z will tell you what socket you have as well, so you know what to look for there
ok, see the watt ratings on the chips?
you'll need a motherboard capable of supporting at least 125w for the 6400 chip,
what mobo does cpu-z say you have?, google that for the specs and you'll see what it supports,
mobo: Dell OCT103 versionA02
i cant find anywhere which says it.
plase can you look for me ?
found this thread from google, the guy didnt have any luck, seeing as your working with a oem Mobo (Dell massproduced inhouse crap) I'd leave the current chip in there, there not really designed for upgrading as dell want you to buy a better system from them, I would say if you have a budget, pop a post on homebuild and see what we can build for you over there,
I wouldnt throw money at a dell though, just not worth the time effort or money tbh