I use the SUS feature pack with SMS 2.0. It took a while to get everything working correctly mainly because Microsoft does not offer an instant gratification button. You have to make sure you get s_scan advertisement to run, and then get the hardware inventory component to run, then get the sync tool to run, then deploy the package with all the updates. I still haven't got it to detect ALL of the needed updates, but it finds most of the ones the machiens are missing.
A much better, although more expensive tool, is the Shavlik update tool that uses HFNetchk. You can push out SP's and security updates. I started using it on my servers to help keep track of who was missing what, but since we have an existing SMS environment, I popped the feature pack on for the clients to get updated. Hopefully I can straighten out the remaining issues and get all the machiens up to date. Make sure you install SMS 2.0 SP5 before using SUS though, it's supposed to decrease the amount of time the hardware inventory update takes (as well as some other things).