Vista - Internet page loading problems

So heres the problem, our old computer just crashed a while ago and a couple of days ago we bought a new gateway. When we got it home and i started it up ane the internet was unbelievably slow. By tweaking a few settings i did get my speed up but some websites such as myspace just will not load. They did not load before i tweaked the settings and they still will not, it is the same in both IE and Firefox. It will just sit with a white screen and not load. Also i downloaded Windows Live Messenger and it will not let me log on, and also with Itunes i am not able to sign onto my account. I just dont know what else to do.