Differences in IE8 behavior between XP, Vista, Win7?
There are at least 6 versions of MSIE 8 and there are likely differences in layout due to bug fixes in the latter releases. A list of versions is available on Microsoft's support site:
http://support.microsoft.com/kb/969393
MSIE8 on Windows XP is version 8.00.6001.18702 and on Windows 7 is version 8.00.7600.16385.
There are some differences regarding css. When I used two divs, the first floated left and the second overflow:hidden; width:auto; IE8 on windows 7 rendered it correctly whereas IE8 on xp sp2 rendered the second div giving it incorrect width. Wierd!
I have had significant problems on IE8, working from a windows 7 machine I tested the site in IE8 using the standard mode the quirks mode and the IE7 standards mode and had no issues, however my client was using IE8 on an XP machine and told me that there were issues with the layout. I checked the site and it had displayed with significantly different styles.
So yes, there is a difference between IE8 on XP and IE8 on Windows 7.... though I have yet to find out how these differences are happening and how to solve them.