What problems are you having with 10.3.9? Did you repair permissions after upgrading? It’s rock solid for me – let us know what your system is comprised of – that always helps…
If you must go back, you’ll have to do a clean install of 10.3.3 and then run the 10.3.8 updater (if it’s still around on the Apple site). A search at apple.com should find it if it’s there.
pvw
G5 DP 2.5GHz / 4.5 GB RAM / 2x250GB SATA / OS 10.3.9 / FCP 4.5 / QT 6.5.2