It depends on which skin apps and whether you're upgrading from XP or Vista.... and not all Stardock apps are running in Win 7 as yet.
Windowblinds does, however, and skins created for Vista seem to run well in Win 7, while some that were created for XP do not run so well. It's a matter of trial and error there, uninstalling what does not, I guess.
ObjectDock runs well in Win 7 and I have yet to find an earlier OD skin/background that does not apply.
LogonstudioVista skins apply in Win 7... Haven't tried one as yet, but I think LogonstudioVista//Win 7 converts XP logons for use in those OSes.
CursorFX works in Win 7 and all skins created for it seem to run fine.
Iconpackager 5 runs in Win 7 and applies most earlier packs without issue... though in some cases the package preview is not visible. Hopefully there's a fix for this soon.
As stated above, some apps have not yet been updated for Win 7 and will not run: eg; Bootskin; Dreamscene; WindowsFX and etc... Impulse advises which apps are not as yet Win 7 ready to help avoid confusion, possible system errors, etc
Hope this help. 
