Here at my shop we run a virtual Core, so for me, before any upgrades,I do a few things. I take a snapshot of the server which I can roll back to if the upgrade bombs and I make sure my nightly SQL database backup is in place. With those two precautions in place I can basically fix any problem that might occur, from system death to database corruption.
It has worked well so far!
If you have maintenance / support agreements with LANDesk, I would contact them, let them know what you are doing and ask them if there are any additional hot fixes or "component patches" you should be installing after SP2.
to find out more about component patches
There have been numerous hot fixes released.