Solid Works is trying to stick it to autocad...
they have come up with a translator for autocad that can read and write dwg and dxf files throughout all versions... it is excellent for working with different versions older/newer makes no difference. with this download you can open any dwg/dxf in your non-current acad.
mdt 2006 can save acadr14 dwg/dxf
acadr14 can read/open acad 2006
i'm not one to download freebies, but this is a great add on and it's FREE
no annoying email/phone calls etc...
hope this helps