Vista won't connect

I have a 7 day old Dell pc with Vista, internet satellite and using a Linksys
wireless router connected to a another pc that's XP. Today, the Vista pc
shows it's online but the only thing that will open is Yahoo Geocities.
Everything else gives me a DNS error. Dell told me it was a conflict between
Vista and programs and hardware I installed. I installed my backup hard
drive and my HP printer. Both are Vista compatible per their web sites. I
installed 3 software programs: Audacity, Spybot and Yahoo messenger. They
said the only thing I could do is to reformat and start over. I don't want
to reformat a brand new $1800. pc. My internet provider, WildBlue, said the
modem was bad. I asked them how could that be possible when the Windows XP
works perfectly? They didn't have an answer so I finished the call. If I
remove the router and hook up the cable directly from the modem to the Vista
pc, nothing changes. The Windows XP works no matter how it's hooked up.
Please help me get this pc back online. Everything worked perfectly for 6
days now I'm stuck. I did uninstall all the hardware and all the software I
installed but nothing has changed.