if your software works now, it should work after the upgrade.
i've upgraded in the past, and most things worked ok, except my tweaked services had to be retweaked, and i had to reinstall punkbuster. i also had a problem with daemon tools after the upgrade, but someone on this forum quickly told me how to fix it.
all your data should be ok too, but it wouldn't hurt backing it up onto a seperate partition.
however, as the latest build is the RTM, it's advisable to do a clean install...it's up to you...
good luck, and enjoy your new OS!