Cisco Network Assistant stores this data in "c:\Documents and Settings\\.networkassistant".

If you have one or more communities defined you should find a communities sub-directory containing XML files based on your community names.

In theory, if you transfer the communities sub-directory to the new machine you should see all of your communities on the new machine. Alternatively, if Network Assistant needs some of the other data stored in the root of the .networkassistant directory you will need to transfer .networkassistant and all of its sub-directories.