I use AutoCAD Map 2002. It has some extensions for GIS. I have the upgrade to the 2007 version but don't dare install it till we get our current projects finished. At some point I'd really prefer to switch to ArcGIS, but for right now the 2007 version of AutoCAD gives much needed enhancements like being able to print in 16 million colors instead of jut 256. There are various levels of backward compatibility, but my brother and I are very good at finding the features that aren't compatible.
I know someone who took a couple courses in ArcGIS from the Geography Dept at a major university. Not as intuitive as AutoCAD from what I can tell. However, I would imagine knowing ArcGIS would be a highly valuable specialized skill. My very first job was mechanical drafting.