Hey Thomas,
Coming back to this question, let me state that normal gameplay is pretty much unaffected on a decent video card (yours should be able to handle it) but the extended scenes -- such as duelling or dancing -- are really, really painful.
I got a chance over the weekend to try Pirates on a machine similar to mine with an ATI X800 video card, and it was an absolutely remarkable (and more enjoyable) difference. The picture was 10x better (all the "details" sliders were on max), the colors were brighter and richer. It was very, very cool. The X800 however could be considered a little TOO much improvement as things like duels move in faster-than-real-time movement.
The funny thing is, the guy who owns the machine was told by ATI that the card is too fast to handle setting a monitor at 70 hz, so he had to crank it up to 85 hz (the highest his average 17 inch monitor could handle at 1024) just to use it.
I didn't get a chance to try out something like Doom3, which would strongly push the X800, but I would honestly suggest that you (and I -- if I were able) look to buying one of those 6600 GT or even perhaps an X700 card, if you have PCI-express. If you're like me, the most appropriate card you could find would be a 6600 GT/AGP which can be found for $229 US at the current time. (direct link to item at
tigerdirect.com)
I figure that compared to our current cards (your 7500 and my 5200), 80 fps in Doom3 generated by the 6600 GT would be sufficient (according to
the testing at anandtech.com) and would last you a long, long time before NEEDING to upgrade (as we do now).
I've used my FX5200 for about 4 or 5 years. I gave about $200 for it (actually I burned out the first two and this is my third replaced under warranty -- bad mobo), so if I can swing the money tree (Christmas is coming!), it may be time to upgrade.
Wayne