Ouch, from Unix/Linux to Windows.  Goodbye nice scripts...
I guess you can get perl for windows but again I say ouch.

Upgrading/Changing the master server shouldn't be too hard, involved
yes, hard not necessarily.  Theoretically you just install the software
to the new media server, and restore your netbackup catalog to the new
server.  Make sure you decommission the current master server correctly,
or else you will have all sorts of inconsistencies in the media/volume
databases.  Update all of the bp.conf files on your clients to point to
the new master server.  

You also have to worry about licenses, zoning in tape drives, changing
any in house scripts that have your master server hard coded, and look
out for any gotchas that may exist when moving OS platforms, i.e. is the
version of NetBackup you are using more reliable on a certain OS, will
the OS you are moving to have a different set of issues then the one you
are on now has, stuff like that.

There isn't a great deal of documentation, and (this is my own
conspiracy based opinion here) when you call Veritas they say oh that's
nasty, but we would be happy to have professional services come on site
and help with the migration.  (Lots of money)  Funny how that one works.

Taylor