I don’t know if you guys are using it, but there is a great online tool for easily conducting browser compatibility testing and preview web pages across popular browsers.
It’s called Adobe BrowserLab and you can find it here: https://browserlab.adobe.com/
I really find it extremely helpful, maybe it will help you too.
This is more for IE but until now the only tool that I’ve found to be accurate was VMware player (or any virtual machine). I have 3 separate installations of Windows XP/7 and I can know for sure how it looks under IE7, 8 and 9