Q:
A: Not necessarily, The internal architecture of the cards are different. The 8500 will be able to process information quicker internally as it has a faster GPU but may be slightly stunted when it comes to passing that information to and from the rest of the computer. This is because it may have a slower bus with less bandwidth to play with than a 7800GT. The 7800GT won't be quite as quick internally but may be able to send and recieve information quicker because it may have a faster bus & more bandwidth. The chances are that the 7800GT will also have more memory to play with too so you will be able to ramp up the graphics options more than on the 8500GT. The main change is in developing technology, further graphical enhancements & instruction sets will have been introduced with the 8 series cards that the 7 series card will not be able to use. In short, in terms of raw power they should both be about equal, the 7800GT may even be slightly faster when it comes to performance (as it is a high level card & the 8500GT is a low/mid level card). Do a search on wikipedia & you should be able to compare the different GPU's yourself.