Windows 7: Wireless extremely slow for me but no one else

Last week we switched internet providers. I'd had no problem before with internet speed. I can connect & it says Internet signal is excellent. But it is so slow I can't even check my email.
Average ping is over 300 and often goes up to 800 before disconnecting.
I've ran Spy Bot Search & Destroy and got rid of anything it said was suspicious.
My service provider says to reformat my computer but I don't really want to and can't find my discs.
I can access Internet perfectly fine at other places.
Everyone else is having no problems.
All suggestions welcome ! I go back to University in a week and really need home internet !