"If you want to attempt to force Firefox to accept old add-ons, there are ways, but prepare yourself for consequences: bugs, stability breakdowns, and tampering with advanced settings. Two Firefox 3.5-ready add-ons that often correct incompatibility are Nightly Tester Tools and MR Tech Toolkit. CNET Executive Editor Tom Merritt shows you another way to teach the new 'Fox old tricks. Both methods essentially override the maximum version number rule that keeps Firefox from loading an add-on that's been approved for a previous version build, like 3.0. Nightly Tester Tools, for instance, is cleared for versions 3.0b5 through 3.6a1pre." - JohnDu™