asp.net upgrade site from 2.0 to 4.0

Question

can we install or use 4.0 framework on windows 2003 server ???

basically right now we are using 2.0 framework on windows 2003 server.

we want to update framework from 2.0 to 4.0 on same window(2003 server)

Does it support??? one of my friend saying window 2003 server doesnot support 4.0 framework ???