I have gone through a few gfx upgrades that were leaps in performance but I would have to agree with SlipperyPete. The Voodoo 2 12meg card I had way back then meant that I was either playing a game or not playing it. That's just like going from being a fat kid watching another kid eat cake to being that fat kid and eating the whole cake.
Onboard Graphics --> 7900GS. Never had a dedicated card before this and was amazed at what I could do with it and how much faster my pc seemed. Then a couple of years later
7900GS --> 8800GTX
I had no problems playing anything with max settings, which was immense for me seeing as I had just had cast-offs until then.