Tiff, I say as you don't know what type of games you like and if you'll enjoy them.

Go into your local Game shop. Find the PC games. They always have deals on their cheaper games. Most if not all will easily run on your PC. You could get 3 for just £10. Pick any 3, chances are they will be good if they are still being made.

Then choose what type of games you'd like more of and ask us. I just can't see the point in spending any large wedge if you may not even get on with games on a PC. Many people prefer to stick to a PS2 or XBOX etc.