backing up to my computer

I put a 80gb HD in my computer so that my dad(on my network) can back up to my computer in the event that his computer crashes(again) he will have a backup of his vital files. what kind of performance effects will this have? i assume he will do a back up once every 1-2 nights. also, are there any extra security things i may want to look into for protecting this drive? i guess my computer would be almost like a computer server...he was thinking of putting his music on the drive and he could just access that way.

I have a hd in my shop computer exactly for what you are describing. I backup important stuff from my office and laptop computers. There will be no performance hit on your machine.