I am pretty sure you are limited to very early LGA 775 chips. That would be Pentium 4 5xx and 6xx series and Pentium D 8xx chips and 9xx chips. You could go with a faster clock speed Pentium D but in my opinion that is a waste of money. You would be spending money on obsolete tech that was not even very good when it was new.
To specifically answer your question a Pentium D 960 is probably the fastest chip that board will support.
Thanks everyone. This is what I pretty much was thinking but wasn't 100% certain. I guess the best thing to do is to just de-brand the computer? I'd much rather do this than get old upgrades but I wasn't sure if my recovery discs would work on the new set up. I don't have the actual OS disk and I would hate to shell out 100$+ for win 7 right now. I'd go with Linux but I'm not that tech savvy. Any suggestions?
I think there are programs that can show you what serial you are using on your OS (search on google ), that is the only thing you need to do a fresh installation on a new PC. I dont think it whould be iligal for your to download a new DVD with your OS when you have a valid serial, just make sure you are not sharing while downloading.