My laptop has both Windows Vista and Ubuntu on there with WUBI being the facilitator of the peaceful coexistence. However, what I either forgot or never realised was that it was the 64-bit variant of Ubuntu 9.04 that has found its way onto the thing. For the most part, it works well but there is one catch that I recently encountered: not every Firefox plugin or add-on is 64-bit compatible. Google Gears is one such example but other very useful and pervasive helpers have the same affliction. RealPlayer is one and Adobe’s Flash is another. Apparently, you can still download the 32-bit release versions and use nspluginwrapper to get them going. That worked for RealPlayer but seemingly not for Flash; more investigation may be needed on that one. Other remedies like using 32-bit Firefox (if it runs, of course) or alpha versions of what Adobe offers can be tried too. It almost goes without saying that I’d wish that there was more awareness of the 64-bit Linux world but I remain glad to have met this rough edge before taking the plunge with my main system.
Update 2014-01-24: It looks as if this problem has gone away now with the growth in maturity of 64-bit computing. Certainly, it does not rear its head on any 64-bit Linux distro that I have used or even Windows, apart perhaps from ensuring that you are using the right JRE for a browser (32-bit or 64-bit).