With PC gaming, it is important to read reviews about games before you buy them. If the reviewer is any good, he/she should be able to tell you if the game is buggy or not.
I feel your pain, however. I am playing The Witcher and, even though it is an amazing game, it has it's fair share of bugs. I finally figured out to set my resolution to a 16:9 aspect ratio to fix some of the graphical bugs.