I have installed Windows XP on my Windows7 and the worst that happens is some line is to high or low or somethins missing.
I'm no pro though. Just my experience.
Im unsure about that but it would be pretty cool if it would be working with a skin that only has V win7 sections skinned.
The startmenu in xp is normally much much smaller than in windows7
PS.
Best way is trying
Your system wont crash if the skin does not have the sections skinned. it will just look odd
Things to test is Startmenu sections like the searchbox -expanded programlist ( left the programs that have the little arrow on them (>) )
Allprograms and shutdown buttons
I just answer bc i also only do windows7 windowblinds, i would like to do a complete all OS skin once but i simply cant do it since i dont have a rig with XP or vista anymore.But i usually skin the vista sections in Skinstudio aswell ( at least for the startmenu )only 2 things i dont skin is allprograms mode and the bottombarright ) both vista sections.
If i had a way to test the skin properly on the previous OS i would skin them also but sadly i didnt find a working ( free ) virtualbox that can do that.
