I cloned my drive as a back up and then did an upgrade. So far, so good.
It went pretty quickly too, less than an hour. With the huge amounts of data on my drive it was either that or do a clean install and let it migrate everything over from the backup, which I'm too impatient for unless there's a problem.
Being an old windows user: CLEAN!
Being an 1.5 year OS-X user: Probably clean, though having doubts. Guess I'll go for Archive & Install what looks to be quite nice 'between' feature.
But still... Think of all the junk you still have from old de-installed software (yes, you've got those files too in OS-X). Or all those program's you don't use anymore etc.
What's better than starting a new OS on a new fresh empty disk, right?
But mmm... i'll wait a day or 2 before installing and i'll keep a close look at the fora for yet unknown bugs (That blue-screen thing with upgrading looks like the first one was maybe found, quite normal if you ask me [Windows XP was a pain in the ass too the first day with me, as was Vista, as was bootcamp 1.0, etc.etc.etc.].
I was supposed to do an archive and install but in the end I just upgraded (I have a Super-Duper clone to roll back to). I have to say I'm impressed, it was quick and apparently flawless. Leopard is pretty much as fast (if not faster) than Tiger. The only problem is that a few apps, like Insomniax and the Growl Mail plug-in, don't work but you'll run into that problem with a clean install too.
Really impressed with Leopard and surprised at how perfect the upgrade was.