You could probably get a few hundred hits
on google with "compare or comparison and
Reiser* and ext3" ...
But in short: ext3 allows for a full roll-back restore
(keeps a WAY bigger journal) and is based on
ext2 (switching between the two should be a breeze).
Reiser has been around for much longer in
terms of journaling.
But to be fully informed you'd have to look
at jfs and xfs, too :)
Btw, this is *NOT* a hardware question ;)