newbie home user q - NAS duplicates from Backup and File

Newbie and this is not my area of expertise, so I hope I frame this correctly

Home user of Acronis 2011 backing up my Win7 PC to a local NAS. I'll add more computers in the future.

The bulk of my data is music and photos, both which I need on my PC for editing, etc and on the NAS to be available to other players and computers as my PC is not always available. For this reason I'd like the media data to just be in a file on my NAS at a fixed location in the Public folders. Changes are infrequent and its easy just to copy/paste when there are significant updates. If NAS accessible files are not current, its not a big issue.

The NAS does have storage limitations and I don't want duplicate copies of from both my pc backup and from the cut/paste files I maintain.

Is there a way to have Acronis not back up certain files?

Hope this was clear, thanks