Hello nolamonte,
I realize that this may be a bit off the mark but thought you and others in similar situations might benefit from this tip:
The preserve previous versions of apps (and entire versions of Mac OS X), consider buying a large firewire external drive. Partition it (using Disk Utility) and clone your "previous system" plus all apps to the (adequate-size) partition. Use the 2nd partition on the external fw drive for backing up data.
This gives you a bootable back up drive which also insures you get through possible failure of your internal drive.
My own strategy: I update my main drive (volume) to keep apace of advantages offered. But I leave my bootable (cloned) drive at the "last version" state until I'm absolutely sure the newest system or apps versions are working as I want and need.
Of course, if you don't already have such a back up ext. HD, you should "Archive Previous System" when doing system updates. Clean installs are most needed when you have a "hopeless case" and need to wipe everything.
Anyway: When I got my Mac Pro, it came with iLife 08 of course. I was able to install v. 08 (and then test and reject it) without "losing" iLife 06. (I confess, I think it was a case of having the iLife 06 install disk and just re-installing.) Never the less - I have in fact "saved" all previous app versions because I've always had that external firewire drive with a cloned system and User folder installed.
BTW: I've always used CarbonCopyCloner for my cloning and backup operations. I've tried other backup apps and this is the one I keep coming back to. I've been doing this since 2003 w/o problems. I still use my eMac (1 Ghz PPC - G4) with OS 10.3.9 and it runs happily with a Mercury FireWire 400 bootable back up drive.
Hope this will help you in the future.
macnoel