HELP!

I just bought a Dell Inspiron 6400 loaded with Windows Vista Home Premium. I'm not familliar with the security "features" just yet. I feel that's the culprit for some programs to not work e.g. Skype, Azureus, Limewire

When I load Skype, my internet connection automatically hangs, Skype itself won't connect. For Azureus, tracking fails. And Limewire doesn't connect.

Makes me wanna install XP and let Vista "mature" before reinstalling. I don't even know how to do that.

Please advice on how to deal with the security, and maybe how to delete Vista.

THANK YOU!