Hi,
As much as I like NetWorker, I don't much care for it's archiving capabilities. It's not really archiving at all. It just a backup that can be held for a long time. There's no opp. for meta data, which is essential with any good archiving product.
Anyway, to answer your question.. if you can, I would shutdown the MSSQL services and archive the cold data files. That would make restoration easier than with the hot backup.
If you cannot shutdown the MSSQL services, create a client profile on the backup server with a long retention and browse time. Then just perform a standard SQL backup. If you want to hold the data indefintiely, just pull the tape, and put it aside. As long as the tape isn't re-labled, you should be able to recover the data. Anyone else have any other ideas?
Good Luck!
-ag100