Let the hive mind of Engadget get that for you.
"As someone who doesn't reside in the USA, I was wondering what would be the best way to get internet for my computer in the US for a couple of weeks? If it were Europe I know I'd look for some prepaid data. Is there anything similar offered by American carriers? A MiFi or a data SIM that I can tether from would work, but I'm trying to maintain a tight budget. Help!"
Well, I'm still running NT 5.1 (aka XP) on my cygwin desktop (the other one's Linux), and I don't _need_ an excuse. I have that system to do certain tasks that need Windows, and 5.1 works fine. Why would I upgrade to a new OS when that will cause software problems (bad enough), and will also yield poor performance, probably requiring a hardware upgrade (worse)?
When I get around to replacing or thoroughly rebuilding with modern components, then I'll consider what OS to install, but it looks like NT 6.1 (aka 7) will be out by then, so concerning myself with it now seems pointless.
Again, I don't need an excuse to stay, I'd need a reason to switch now. And I don't see a reason.