A question on Vista to XP

I have brought a new computer and I realised that Vista is not better than XP:Very slow,and a lot of softwares cannot be used...etc.

So I want to format my C drive and install Windows XP.But one thing is that,can I change back to Windows Vista if I would like to?(It is added that Drive D act as rescovery disk.)Can I just press F11 botton on the keyboard to change the XP system to Vista again?