/ext3 is a more advanced filesytem than /ext2. A /ext2 filesystem can be upgraded to a /ext3 filesystem. /ext3 is journaled, so it recovers well from crashes. This increased reliability is the biggest deal. Given a choice between the two /ext3 is a clear choice. There are few other added features too.
Pretty much everyone will agree that /ext2 is obsolete. But at this point, the ReiserFS folks and/or the XFS folks will want to tell you that their favorite FS is better than /ext3. We have had threads like that before and nothing useful came from them. Please remember that our rules state: (8) No BSD vs. Linux vs. Windows or similar threads.
So /ext3, ReiserFS, and XFS have all been mentioned. Let's not have a fistfight over which is best. I'll leave the thread open for now. But it's probable that it won't be open for long. 