I like Nvida's drivers. I'm using a PNY 9500GT 1GB card -- got it for an amazing $30 at Fry's. Works great for me. Of course, how would I know if something else works better? Generally I think most here would agree that Vegas relies on your CPU not your video card so unless you're a gamer no use spending much on the video card. Just get the fastest CPU you can afford with a generous amount of RAM.
None about that specific card, but I have two different ones in two systems - a GEForce 6600OC 128MB and a GEForce 9800GT 1GB - and they both work very well with Vegas 9.
Do some searches in this forum on video cards. There have been many discussions on the relative merits of high vs low-end cards, memory and so on.
You don't need a real high-end card if you only want to use it for Vegas.
I have been very happy with my 8800GT (Nvidia) that is now 2 years old!
Whatever you choose, make sure it is CUDA compatible. Ok, Vegas does not use it yet (oris it ever?). However, some plugins or other programs DO! In these cases you get an overall speed increase. But only if CUDA compatible.
Vegas itself just works with any modern display controller.
as long as you don't use the MS drivers & use the manufactures drivers, anything will do. But if you want multi-monitor out then obviously pick a card that has that. :D
I can recommend nVidia Quadro 1800. Vegas can't use GPU but You will for sure use other apps (like Bluff Titler) to create titles or use vector-based content (3D text for example). Quadro has a hardware antialiasing feature - without it vectors look terrible and You can't asses properly your creations.
Google's Sketchup is a free 3d program that is easy and fast to use (I often use it). It says that it should be used only with nVidia cards. I got an ASUS 9600 GSO for $40 - surprisingly fast for apps that can use it; very happy indeed.