will look for a previous version before it will start the upgrade, but if you have a previous version on CD here's what you do:-
1. Insert the FP CD and let the installer suto-run.
2. The installer will check your registry for a previous version, and when it can't find one it will stop, and ask you to tell it where that version is.
3. When that happens, eject the FP 2003 CD and insert the previous version's CD.
4. Now point the FP2003 installer to your CD drive, and it will look at the CD that's in there. It will find the file it needs and will carry on with the FP2003 installation - asking you to reinsert the CD before it continues.