Vista Tutorial - Internet connectivity issue

So here's the issue I've run into both on RC1 and the public beta from
earlier...

I connect up to my network fine, pull an ip, able to browse shares and such,
can even ping web sites but when opening Internet Explorer and trying to
actually browse, the computer fails to find the site. I even see the browser
status bar acknowledge a dns lookup by telling me the external ip of the page
it's trying to hit but again, nothing ever loads. The other computers on the
network have no issue of course. Another interesting thing was even though I
was unable browse various web sites, I was able to download an update to
Defender during my troubleshooting so it almost seems as if by default, some
level of security is preventing me from leaving the safety of my private
network.

To add some background, the first time I saw the issue was while playing
with the public beta. It was after a few weeks of normal use when all of a
sudden I couldn't get out of the network no matter how hard I tried. This
time with RC1, it started right after the initial install. I've done some
browsing of forums and articles and such but haven't found anything detailing
my issue so I thought it best to toss a question out there. I saw mention in
another thread asking about the type of network card being usedso let me add
that here too. In my first setup it was a Realtek card and this time it's a
Marvell.

Any thoughts?