I stumbled across a cool site today that lets you test what your site looks like in every browser imaginable. Yes, apparently if your page validates against W3C standards then it should work in every browser right? Well, that is what I thought...and it is wrong. Bare in mind that a lot of these browsers are either not in use anymore or represent well below 1% of all browsers.
It can take some time to do the analysis, but the pay offs will save you install every browser known to man/woman :)
Hope this helps,