What's a good freeware for vista that lets me surf the internet while hiding/changing my ip?

I want something free that will still let me log in to web pages, and stuff like that. I've tried using proxy.org and all their stuff, but none of the websites look normal (like gmail, yahoomail, etc) and I can't log in to any of them. Is there any software (like a browser) that I could download? Thanks in advance!