You can upgrade to win7 from vista, just not from XP.

As for wow, just copy the folders over.

For isboxer, there is a post about it on here somewhere. You just delete one file and it remakes it when you relaunch it, updating the paths. It does NOT fix the paths for the keymap icons so if you have those visible, you have to manually edit the paths to show the new location for the icons to reappear.