If you are planning on upgrading to AutoCAD 2008 32-bit, and you have existing LISP, VBA, or ARX programs, will they work? Generally speaking, yes. You may have to make a minor adjustment to your code, but for the most part there shouldn’t be any problems.
If you are planning on upgrading to AutoCAD 2008 64-bit, then you may have some decisions to make and/or work to do…
Either way, I would suggest reading the following documents that describe any required changes and/or suggested alternatives.
will ACAD keep VBA? (Autodesk discussion group entry)