How to wipe computer clean but keep installed software

If you want to completely wipe the drive:

1) Clone drive to an external.
2) Reformat, install Snow Leopard.
3) Use Migration Assistant to import everything from the clone.

In theory, at least, all your apps should continue to function properly if you have Migration Assistant do its thing. Adobe DRM is finicky to put it mildly, but when I migrated from 10.5 on a G5 tower to 10.6 on an iMac, CS3 kept working, surprisingly enough. Can't say for later versions, as Adobe's DRM hasn't exactly gotten more robust or friendly.

If you just want to reinstall the OS, you'd do an install, preserving users, I think, though I think the options have changed somewhat in Snow Leopard, and I haven't yet had reason to do a reinstall. I'd recommend the former method, if you're going to go to the trouble, though.

Of course, if you are willing to do a full reinstall of the OS, seems like it'd be worth your time to do a FULL reinstall, including apps. If anything, reinstalling the OS and NOT reinstalling major apps like Creative Suite or FCP is going to increase the chances of something becoming flaky rather than decrease them.