Acceptable File Types for CAD data
The following is a listing of the preferred file types, in order of probability of success.
Master CAM:

MCAM V9 or earlier (.mc9, .mc8, …)
IGES (.igs, .iges)
Parasolid (.xmt_txt, .x_t, .x_b)
STEP (.stp,  .step)
Pro/Engineer:

Pro/Wildfire or earlier (.prt, .drw, .asm, …)
STEP (.stp,  .step)
IGES (.igs, .iges)
SolidWorks:

SolidWorks 2004 or earlier (.sldprt, .sldasm)
Parasolid (.xmt_txt, .xmt_bin, .x_t, .x_b)
STEP (.stp,  .step)
IGES (.igs, .iges)
Unigraphics: 

Parasolid (.xmt_txt, .xmt_bin, .x_t, .x_b)
UGII (Unigraphics Native .prt)
Although we have the ability to read Native Unigraphics files, we prefer Parasolid over UGII when given a choice. 
SDRC IDEAS:

Parasolid (.xmt_txt, .xmt_bin, .x_t, .x_b) starting with V9 of IDEAS
STEP (.stp,  .step)
IGES (.igs, .iges)
AutoCAD 2D: AutoCAD Native (.dwg, .dxf) R12, 13, 14, 2000, 2002 Includes Layers, Line Types, Fonts, Colors, Blocks, and Attributes.
AutoCAD MDT:

ACIS (.sat)
STEP (.stp,  .step)
IGES (.igs, .iges)
Inventor: Inventor Native (.ipt)
SolidEdge:

Parasolid (.xmt_txt, .xmt_bin, .x_t, .x_b)
SolidEdge Native Part (.par)
SolidEdge Native Assembly (.asm)
Cadkey:  Cadkey Native (.prt)
Other file types also accepted:

Stereo lithography (.stl)
VDAFS (.vda)
VRML (.wrl)
Catia Graphics (.cgr) graphics only
Computer Graphics Metafile (.cgm)