We used add-ons with R14, most if not all of those were eliminated with 2000i (barely used 2000 before we moved to 2000i), never used R13 very much if at all. Are you running AutoCAD 2000i or AutoCAD 2000? IIRC, AutoCAD 2000 was unsupported on Win 2000, but ran, that's one reason we moved on to 2000i. With the add-ons R14 wasn't as good as 2000i, don't remember if 2000 was much better or not, but it probably was or we would have stayed on R14.