I hate to advise people to try and fix their computers by buying parts at random and testing to see if the new part will fix the problem. It is not an intelligent way to do this.
But if you insist (and resist) then I will tell you that the problem could be a faulty video card. The 200 series nVidia and corresponding series in AMD were problematic.
Windows 7 is a very graphics intensive operating system that takes full advantage of the advanced features of a graphics card, which XP did not. Does this make it the "fault" of the OS? No. The more powerful OS simply exposes the defects.
So if you do not wish to bother yourself with doing any diagnostics on your own to see if it may be one of the other, cheaper to fix reasons people get these error messages then you can replace your video card for a start.
Better, if you can borrow someone's video card (of equal or greater version) then you could test your system for a bad video card without paying money to do so.
Be sure to completely remove the old video card drivers
and related software from Remove Programs before trying any new card.