i don't recomend the 260.99 at all, they sorta seem funky, i've read on the nvidia forums and on the 3dguru forums about .89 and .99 drivers, both seem off somehow, and i had instability problems with that driver also, went back to 258.96 and the system seems beter... after awhile of tweaking ofcourse... they seemed to have done something to the system that shouldn't have happend.
i'm also on xp sp3 but here's the differenace, i'm using a geforce 7800gs agp card, still something like this just shouldn't happen.
side note, i had to use driver sweeper after i uninstalled the driver before i installed a new one, maybe that could fix your opengl problem.