Good for you, AVG! But you're not giving your old Radeon card its due credit. The 7800GS is at least three steps up from that card, in terms of processing power. And the whole glare issue, well, it's not really ATi's fault...or at least not completely. Both sides are to blame here. Now, guess what card I used when I got this screenie:
Hint: it's an ATi, same series as yours, with a bit more punch (ok, it's an X1650Pro). I get these results constantly when I pause the game, alt-tab out of it and back, and then go to outside view. Only lasts long enough for me to grab a pic or two, then it reverts to Ye Olde ATi standards.
ETA: Switching to a PCI-E platform is good and well, but for the love of the Gods, stay away from Vista! Make a dual-boot system with XP and Vista if you must, at least until Vista has been Service-packed a few times. I spent a whole weekend trying to get a new laptop to work properly with Vista. I got a 20% increase in white hair in that weekend, trying to get 2- and 3-year-old programs to work. Never happened!
ETA #2: Dave, talk to us, mate! We're getting a bit worried!