Yes, it is worth the upgrade. The faster IPC and higher clock frequencies will be beneficial.
I know some of the Biostar boards were good at OC'ing, but others sucked pretty bad. Depending on some other factors, I would still be shocked if you couldn't get at least 3.6 out of it.
I say go for it.
When the time comes and you are able to upgrade to a newer socket, then you will definitely notice a better increase, but until then the Q9550 is a descent step from where you...