if you are nervous suggest you purchase a cheap second drive and do a clean install on that - then you dont loose anything you have already.
keep the 10.3.3 disc as an archived backup.

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doing a clean install is better.
there arent many issues left in tiger. it works fine.
and not many settings.

you need to install the latest decklink, atto, and aladdin dongle drivers for tiger.
www.decklink.com
www.attotech.com
ftp://ftp.aladdin.com/pub/hasp/hl/ma...ler_MacOSX.dmg

in my experience its better not to install additional ati drivers for now - but its really hard to tell - whether they do anything.