All new Taskbar
No.
you can not degrade.. you have to do new installation
No. Obviously, if you upgrade to Windows Vista, you will have Windows Vista.
windows Xp is better but Vista is slightly faster
Drivers written for Windows Vista are not backwards-compatible with Windows XP. Most hardware that has a driver for Vista should also have a driver for Windows XP.
the windows anytime upgrade tool
They are "compatible" in the sense that many applications that run on Windows XP will run on Windows Vista.
Yes ofcourse, Windows Vista is upgraded version of Windows XP. Obviously it can run Windows XP applications.
"Vista XP" is not a computer type. Vista and XP are both previous versions of the Windows operating system. The current version of Windows is Windows 8.1.
Windows XP is better. Vista is a better at running games, but it is slower and more problematic than XP
Windows Vista is notably far more secure than Windows XP.
No.