Seeing as it is WSS V3 content, I would only be concerned with migrating
the site collection info.
I would either 1) stsadm.exe -o backup -url <url> c:\backup.bak, for
each site collection if there are only a few. You can then restore these
on your new MOSS farm
Or
2) You could migrate the content databases over to the new farm, attach
them to a Web Application, and the site collections will populate
automatically, assuming the managed path exists (it will if both were
installed using defaults)