Vista wasn't that bad as long as you had something better than the home version. Home Premium and higher and you're good. I run OSX and Vista on my MacBook Pro, and Vista on my gaming desktop at home and I've got no problems with it. I've got Windows 7 on another laptop at home and I absolutely hate it because the laptop obviously wasn't made to run 7 on it so it's slow as fuck, but the OS itself is nice. XP I just can't stand because it both looks horrible and it's just annoying to use imo.
Back to the original post, like someone else said try using a different browser (Chrome, IE, Firefox, Safari, Opera), I have a game I run that won't work with Firefox, but it works perfectly with IE. If no browsers work, try installing a browser on a flash drive with all the plugins you need and running it off of there since sometimes school computers are retarded about you downloading plugins for their computers.
Hope this helps.