ftaok said:
Good question. I would expect that the key will still work, but who knows with MSFT's activation policy.
Here's what I would do. Burn your entire Microsoft Office folder onto a CD. Then if the key doesn't work after you've installed Tiger, you could trash Office and load it back up from the CD-R. The copy of Office on the CD-R should retain the activation.
Reinstalling it and using your key again will be fine. There aren't hoops to jump through like with reinstalling WinXP too often.
The preferences files are not stored in the MS Office folder. All your copy will contain is the same things as on the installation CD. Your preferences, which may be nice to save for your settings, are found in two places:
~/Library/Preferences/
~/Library/Preferences/Microsoft
(~/ is your Home folder)
Also, to make your life much easier, just use the Archive and Install option on Tiger's installation DVD. It renames your old System folder and gives you a fresh installation of Tiger. It also preserves your settings and users if you leave that option checked.