Bricscad, a near 100% ACAD workalike, will run your lisp routines, etc, if any,with the natural caveat of version compatibility - older versions of autocad compatible lisp routines (and VB routines) sometimes require "fixing" to run with newer versions of autocad. Bricscad may be affected similarly, but all being equal, Bricscad runs your autocad lisp routines. The Bricscad menues will be familiar to anyone familiar with AutoCAD classic icon menues, but with some changes to the icon toolbars over the years, you'll do some command hunting as your familiarity increases. Typed commands and their typed options will be familiar tho. What WON'T be familiar is the U-I stuff - options dialog boxes like where you set settings, etc are completely different from AutoCAD's, and will take some learning, but work fine once you've found where Bricscad sets the same setting as AutoCAD . Again, it's really where to find the same thing in a different menu system. That being said, the toolbars for the commands themselves will be very similar.
Progecad is another alternative that will run and function with near 100% compatibility. It will seem much smoother than Bricscad for daily use, and will do FINE for normal 2-D piece parts AND assemblies. Advantage to PROGECAD is that its VERY smooth, looks identical to the current "classic" ACAD interface, including toolbars, Icons AND internal dialog boxes like the PLOT dialog and the Properties dialog, and the OPTIONS dialog. It will run your autolisp routines, VB routines, etc, with the same caveat as the Bricscad one, above, and really for all practical purposes where you're concerned, may meet all your needs. You might find it a smoother transitional program to use while figuring out your final solutions over the next couple of years though, than either Bricscad or MODERN Autocad. Main weakness of PROGECAD is that its 3D isn't as robust as AutoCAD's or even Bricscad's, but its good, and may be sufficient for you to begin to experiment with early 3D while you're successfully producing 2D content. PROGECAD does true ACAD-Like 3D (including Booleans), and its 3D ACIS components go in and out of ACAD 3D with no noticeable problems.
Bricscad's 3D is more robust than PROGECAD's, and you might like its results better, but this may not be enough to tilt the question in favor of Bricscad over PROGECAD.
BOTH are good alternatives to AutoCAD, and FULL COMMERCIAL LICENSES can be had for either, in the $500 price range, with $1000 - $1500 for top-tier "Platinum" versions of either. I think PROGECAD doesn't go as high as $1500, but your research will tell you more than I can in this post.
Both offer excellent user support.
Both read and write DWG with full 100% compatibility, as far as I've been able to determine, ESPECIALLY in 2D parts and assemblies.
Both run JUST FINE in Windows-7, 32 or 64 bit.
AutoCAD is far more expensive, and actually may not meet YOUR need, especially for the price. However, that may not necessarily disqualify it as an alternative to consider as you plan your near, mid and long - term strategies. For instance, native ACAD 3D is very strong, and doesn't carry the burdens of parametric 3D as in Solid Works and Inventor. Alternatively, Pramatric 3D (Iv & S-W, etc) offers great potential return in automation of 3D production, drawing output and future changes and edits. If you decide to move into a SERIOUS use of 3D you may want to consider that avenue.
For now, 2D can be WELL achieved by ACAD, Bricscad and PROGECAD as outlined above, with the advantages and limitations as mentioned. Basic robust 3D can be achieved using ACAD. Basic strong 3D can be achieved with Bricscad, and Basic good very useable 3D with PROGECAD. The 3D-to-2D tools for converting the 3D component into 2D views work similarly in all 3, with some minor limitations, but all 3 are good.
Finally, there may be other AutoCAD workalikes that are even closer to AutoCAD than these two. These are the two I'm familiar with, and thus are the two I suggest starting your searches with. Any of them will give you a free trial period, and both are worthy inexpensive alternatives to AutoCAD.
BTW- Anyone truly familiar with ACAD r-14 AND Win-XP and ACAD 2D Production, would have known EXACTLY what your working goals and limitations are, and would have been able to answer your initial question as posted.
Good luck in your search, and Please post back with progress and lessons learned along the way ?
As always - proceed with caution !
-C.