Guys, this is a TOSHIBA problem, not a driver problem, or even a Vista problem. I have the P100-ST9012, which came preinstalled with XP Pro. When I install Vista (keep in mind, this is a retail copy of Vista, not from Toshiba), with the Toshiba drivers, I get the EXACT same frame spikes. When I use LV2Go drivers (modded nVidia drivers), they work the EXACT same way. The reason I know it's not a driver/Vista problem is that people with the same chipsets on different brands of laptops have no problems whatsoever. This appears to be a Toshiba-related issue.
Again, though, don't let anyone (namely Toshiba support) try to tell you that this is a Vista or nVidia issue, it is THEIR issue, and THEY need to fix it.