Debbie,
If it is an upgrade edition then it will need the existing version on your
hard drive or it will not install. I am not sure what will happen if it is
not an upgrade as it will either :-
1 give you a message to say there is a problem because of the earlier
version;
2 overwrite the existing version; or
3 install without touching your existing version.
Unfortunately I am know very little about 2007 but hope that my advice is
accurate.
Viv
