Ok, you have the new and old AutoCAD installed, how do you go about migrating your settings to the new program? Should you use that wizard that pops up the first time you run the program?
No! Until you're sure the AutoCAD (or other vertical, Architecture, Inventor, Revit, Max, etc) works consistently you don't want to migrate anything. Let it run for a few days without any changes first. If you migrate settings and receive errors, how do you know what caused it if you have not run AutoCAD without the changes to ensure it works? At this point I typically recommend a very clean uninstall, reboot and reinstall, then run it without migrating. I've seen migrated menus cause errors in AutoCAD.
Note: This post focuses on AutoCAD-based programs, you may not be able to do some of these migrations with other programs like Revit, Inventor, 3ds Max, etc.
Migrating Menus/Profile using the wizard:
Alright, you've run AutoCAD for a few days and now you want to migrate your settings. Ahh, that's easy, just run that wizard that popped up the first time you ran AutoCAD. For example: Start->All Programs->Autodesk-> AutoCAD Architectural 2010->Migrate Custom Settings and pick "Migrate from a Previous Release".
I prefer to manually migrate (actually Import) my custom menu. I created a custom menu back around AutoCAD 2002 and I just use the CUI dialog to load my partial menu. This way I can have my menu in several AutoCAD versions all referencing the same menus (no duplication) and I can quickly remove my customization if I need to troubleshoot an issue.
You can also manually migrate pieces of your menu (toolbars, menus, etc) by using the CUI (that's Custom User Interface for those keeping an Autodesk acronym dictionary). In the CUI dialog select the Transfer tab. On the left display your Main menu and on the right Open your old or custom menu. Then just drag-n-drop from the list on the right to the left. Using this method ensures you don't have all those extra Workspaces showing up in the list.
Migrating Profiles is typically fine, but if your migrated Profile does not work and the normal one does, then you need to spend a lot of time figuring it out. I do not migrate my Profile. I go into Options and set the settings I want, it takes MUCH LESS TIME to manually change the new Profile than to troubleshoot a broken profile. Change your settings on the "Files" tab last. Only modify a few at a time then exit and go back into AutoCAD. If/When it breaks we don't want a list of 30 changes to go through.
Migrating Plot information:
Should you re-use old PC3 files? what about the CTBs and STBs? I typically recommend different folders for sharing PC3s and CTBs. You can have something like the following folders for your PC3 files.
Then copy your old 2009 PC3s and CTBs to the new folder. NOTE: Do not copy any shortcuts from those folders. If you do then you will have very bad performance issues sooner or later. I've seen some systems that would take 20 minutes to bring up the Plot dialog box.
Setup a test environment and test these all out before you spend a couple hours getting AutoCAD installed, manually migrate all your settings only to Crash AutoCAD and have to spend another few hours only to find out your old VBA application won't work in the new environment. Only after thorough testing would I migrate these and then I'd only do it manually testing after each major piece is put into place. Your test environment may work and the users environment may not due to permissions, access to drives/shares, more restrictions in Anti-Virus/Spyware, Group Policies, etc...
Third Party Add-on programs:
Check with the 3rd party add-on manufacturer. Their version of the Lisp/Scrip/VBA or ARX may not be compatible with this version of AutoCAD/Revit/Inventor/MAX/etc...