Vista Ultimate plus 2Wire Internet connection problem

I just upgraded from XP Home SP2 to Vista Ultimate (32). Even though it was a
pain getting Vista to recognize my Raid 0 set-up I finally got a good install
after a few failed attempts. But now I have a PC that can't connect beyond my
Network or even see the Internet.

I have a 2Wire 1701HG Gateway (or HomePortal) which has worked great on my
home network for a year or more. On occasion the Network and Sharing Center
in Vista shows I have access to the Net but IE7 will not open any websites. I
have run every Help topic I can find in Vista and several off the Web from
this second PC next to it. But nothing has fixed the issue. 2Wire has nothing
on their site concerning Vista. And I am fairly certain that is the issue.
Our X-Box 360 and my daughter's PCs both still access the Net fine.

I work for at&t so on Tuesday I will bring home a test modem I use at work
and try it out. That will help me determine if it is a firewall or router
issue or something else since the SpeedStream I have in my work van is a
single modem. Either way if there are any suggestions or possible routes to
try before then please post them so that I can try them all. Thanks.

My system is an AMD Athlon 64 X2 4200+ (Dual Core Socket 939) on an Asus
A8N-SLI Premium mobo running a single e-GeForce 7900 GT video card with 2GB
of OCZ RAM and two 250G WD 7200 SATA2 OEM HDs (WD2500KS-OEM) set-up in a RAID
0 array. I have disabled on-board sound and use an SB X-Fi Platinum sound
card. Not sure what else to post beside I have already updated to all the
latest Vista drives where available.

Note: Driver version for the nForce4 is 15.00 ( Release Date: February 5, 2007
WHQL Certified )

Thanks for any help you can offer, peace.