Rated 5 out of 5 stars

here is the deal i have no clue if this is right but i managed to get it to work with out bypassing the compatibility check.
first i installed extension developer. add-on. using that extension (from the tools menu) selext extension builder.
just to note that in order to find the file you need to set the setting to view hidden files.
browse
ypu have to go in to the for vista (C:), user, "your profile name", appdata, roaming, mozilla, firefox, profiles, orptcwat.default, extensions, {31513E58-F253-47ad-86DB-D5F21E905429}
edit install.rdf
scroll down to the bottom and change firefox MAX VER: to 3.1.0.*

save close and restart firefox.

it should work.
also if you had minimize to tray enhancer you can do the same. i have not tried it yet .