Thanks, Kiwi, for that info. I will definitely be appreciative of it when I do buy a new card - I find all the numbers and stuff quite confusing.
Actually though, I just bought the game anyway to see what it was like - so if it was completely unplayable, I would buy one then. In fact, it's really quite good! I am on low quality (lol it was very disheartening when you install and then go to play and it works out what level graphics you get and you get the rather blunt 'your graphics quality is set to low', like yeah, Bethesda, I know my card sucks you don't have to rub it in

) so I can only imagine what high quality must look like, but I am pleasantly surprised! Certainly nothing like the screenshot Zink posted here of what I could expect. The only problem is that occasionally when I am wandering about people tend to pop into view only when I am almost on to of them and they haven't been there until then