If you run PMIMport before doing the migration all of your patches that you have staged will be restaged automagically for you.  THis will also be the longest part of your import as the patches are redownloaded from MS.
Drop me a note with other questions.

Hello Lillian
In my migration I had a lot of error messages from NS6 SWD Agents.

In these days I try to uninstall the old swd-agents. I will update this post.
The installation (inplace) and migration of NS6-Altiris-Agents required about 3 hours.
Please look for hotfixes first after installation. There were some not included in the download of SIM. I had even a performance improvement after applying them.

Gunnar