You should be able to, it really depends on how you installed that second version. ( during the CD install, one of the options is something like " install into a new windows folder, but leave the other one" - did you choose THAT?)
Right click on My Computer, then Properties, then Advanced, then Startup and recover section, click Settings, then look to see what you have there under "Default operating systems".. do you have two selections?
Older junk I typed:
There May be be complications.

If you have the room, just leave both Windows directories, and just go into your
C:\Documents and Settings\Plopyourusernamehere\Start Menu\Programs
and see if the apps work.
Trouble is, if the apps use things like %WinDir% (variables), it may look in the wrong windows folder for its dlls and such...
[This message has been edited by FieroRumor (edited 10-10-2006).]