I've been unable to install 10.6.3 on my Mac Pro. Downloading through software update always resulted in the update failing, and trying to download the combo update from Apple's site always produces a corrupt DMG file.
I've been told this sounds like a dying hard drive, so I got a brand new drive and installed Snow Leopard fresh onto it. Now, Software Update doesn't even suggest 10.6.3, and attempts to download the combo updater still result in corrupted DMGs.
I'm really not sure what the problem could be, at this point. Is there a weird hardware quirk in the Mac Pros (I purchased mine in January of 2007) that could explain this? Or anything else I could try?