sketchy19: I have Gothic 2 on Steam and have been unable to play it so far. Apparently it has issues with running on Windows 7 and up. I was hoping to buy this here if it has no issues.
On my steam version, Gothic 2 refuses to launch even with the starter mod, I also tried running in windows xp compatibility mode.
I can only go by my own experience: had more issues with my old XP machine such as jerky motion in some areas then I do with my win7 machine. I do have troubles with videos - opening credits (for some reason, that doesn't bother me :) ) and occasionally with cut scenes. Like Arkose said, its likely a machine issue not a game issue (so no way of fixing it via patch, etc).
Steam publishes a lot of games that are not compatible with their system - they know this but the scum refuse to warn people. Usually the fix is to remove the game a far away from the Steam system as possible by making a new folder for it with a new name and directing the computer to look there rather then the Steam folder. There are some tricks involved with short cuts, as I recall.