Been a while since this thread was updated. Time to fix that.
XOP
So what is XOP? It's a shmup that used to be sold, but the author decided that it was a failure as shareware. So, he made it freeware. The graphics are bright and colorful, there's little flicker or slowdown, and it has a strange mixture of old DOS and Amiga Euroshmup influences in background and ship designs/colorings. Plenty of stages, several modes, and lots of options to tinker with. It's not a bad game at all, and despite how it looks, it was indeed made for new PCs, so it runs in XP without any problems. Oh, and it's got plenty of bullets and enemies to dodge, as it has a few roots in the Manic shmup world too.