I don't know much about the viper cards but I don't think it has the equivalent of the Blizzards CyberPatcher. Seeing as you mainly want to play games I wouldn't worry about it much. There is a program called Oxypatcher that does the same job anyway.
I can honestly recommend a Blizzard 1260. I've had one for two years and it has given faultless performance. Games like Quake /Payback/Descent are feasable on it (only at low res). Workbench really flies with this card and loading up JPG's, decoding web pages are so much faster. Your 1200 really jumps in performance and multitasking between multiple programs suddenly becomes a reality. I really can't recommend it enough. Also, I would say it is much more compatible with older software than a 1240. I know this sounds bizzare, but its true! But that's not too relevant since we have whdload to install all those old games
