Douglas - Thanks for the information. I changed the Compression methods to see if that helps.
Just checked the fragmentation level - wow, I'll need to work on that.
The answer to your question about the files, about a 50/50 mix, there are tons of small files, and a bunch of larger ones.
Data being backed up is MS Exchange, and data files (some video files, then normal "business" docs - letters, spreadsheets, etc.)
Everything is local, 1 server is backing up to the NAS over a GB ethernet crossover cable.
TrendMicro Office scan is running on the Windows Server, the NAS is running a linux varient and I do not think it has an av package on it (or it might have clamav, not sure).
If that brings anything else to mind, let me know.
Also, I'm very interested to read the Performance articles from the Symantec techs.