Vista network is testy

Hey,

Recently, i purchased Windows Vista Ultimate for my pc. and everything was running just fine... but then i tried to network with a Xbox360.. but my computer was refusing to network with it. Being the stubborn kid i can be, i kept tweaking with the network stuff untill the xbox360 and the computer could network.

i guess without knowing it, i screwed up my networking majorly.. because my internet cuts out a whole lot, or just doesn't work PERIOD.. right now im on XP so im not having problems...but idno. just recently the internet...just died, literaly. i cant get it back on no matter what i do to it. I was thinking about putting in my PCI gaming lan card but i don't think that would work.

Is there a way to.. uhm rollback my networking on vista? Or a way to completely reset the networking stuff? or maybe somebody could tell me a simple way to fix this problem?

Any help...would be appreciated. thanks