Sharing applications betweet Win2k and XP

I wonder if there is a way to share the applications between Win2K and
XP Pro installations which reside on the same partition.

I have an older installation of Win2K with loads of applications. I
have just installed an XP which ended up on the same disk - not by
design but by the stupidity of the XP install which did not offer me
the option of upgrading Win2k but decided to install XP "on the side"
of the existing OS. In effect I ended up with "dual boot" machine with
C:\WINNT storing Win2k and C:\WINDOWS storing XP.

Other than that everything is untouched, namely C:\Program Files where
most of my software is installed. Attempts to execute anu apps from
there when I boot into XP are failing with the message "Application
must be installed to run".