Virtual machine test suite

I just got some VM software installed on my MacBook in order to have a test suite for cross-compatibility on websites etc. I need to be able to test for Internet Explorer 7 and 8.

Am I right in assuming I shou开发者_开发技巧ld install both Windows XP (with IE7) and Windows 7 (with IE8) to get the most optimal setup?

the result of testing the website with ie7 and ie8 doesn't depend on the windows version only on the browser version. You can also run the ie8 in the compatibility mode but I made the experience that the result of ie7 and ie8 compatibility mode is not 100% the same.