Windows 7 isn't "unstable." I mean, any operating system out there could always be "better", but I would hardly say Windows 7 is unstable. Have you checked to make sure you have the latest and greatest drivers? The fact that you're having graphical issues with MW2 suggest that you may have a video driver issue. I had similar issues with Bad Company 2 on Vista. While a new graphics card driver helped those issues, I still have *some* weirdness that I contribute to being a Nvidia driver issue, however with each driver release things *do* improve.
Have you tried to avoid putting the computer to sleep? Are you using suspend or hibernate? I for one hate hibernation and avoid it on any OS platform. I have yet to see hibernation work without issue flawlessly day after day. If I use any sort of sleep setting, I use suspend. I forget what it's called on Windows, but "suspend" is what it's referred to on Linux. Where it suspends everything to RAM and uses a bit of battery to keep things flowing, etc. Anyway try using without that. If your issues are cleared up, perhaps that's the culprit.
