Ok, we know you're out there. you've been running CAD for years. AIX, Solaris, IRIX, yes, even that other OS.
Now you've discovered Linux. It's stable! It's fast! It's free! Next, you need a CAD application that will run on Linux. What will best suite your needs?
Qcad? It's GPL and uses DXF as it's native format.
Varicad? Commerical, but it does 3D CSG-Solids, reads/writes dwg's.
Cycas? Commercial, 3D, exports to povray for rendering.
Or maybe you have a Win32 CAD that you're running with wine
What ever you chose or even if you have not decided, here is a place to talk about CAD on Linux.