Both Tim and myself use FC5 here in the lab.

Tk/Tcl 8.4 will also work with analysis and I believe these come with FC5. I find yum very helpful when administering Fedora. Try using yum to search for the tcl/tk packages and the tkinter too. Then a simple 

$ yum search <package name>

$ yum install <package to install>

should work. The advantages of using yum is that it takes care of any dependencies the packages may have and 

$ yum update

keeps your system up to date in one fell swoop!

Let me know if you have any more problems... 

Dan