Rather annoyingly to use Google Gears (Google's offline feature) in XP, you have to have admin privledges. This is because the installer, an .msi package, has a registry tweak so that it works in IE in addition to Firefox.
I don't have admin access but I want gears, so I downloaded GG onto a machine that I do have admin access to, grabbed the files that get deployed, zipped them up, and renamed it to an .xpi (Firefox installer file). And it works!
Here it is: google gears for xp .xpi
http://mitchellfamily.ca/blogimages/gears.xpi
