You have to expose less, much less, than you would on a regular shot of the same scene but not having the sun. This will produce a more visible noise, but you will get the most of the sun. Another possibility is to take 2 shots, and severely underexposed to recover the sun from.
The developing stage is really important; use a RAW developer with a good control of highlights. ACR is not. DCRAW with its -H 2 option can recover many highlights and provide good results.
Usually a problem is to have big areas around the sun with not all, but one or two channels blown. This produces strange and incorrect colours in the area. Look at the somewaht orange ring surrounding the sun in this picture:
A correct development with DCRAW can produce this:
