leefal:
I don't think you can csiman, the ps3 can only receive from the pc but can't send to pc.
I recommend deleting everything and saving only the essentials like game saves, you can download the demos again and what ever games you've bought from the ps store. It's a bit of a pain but if you haven't the tools to save the entire harddrive it's pretty much your only option.
Thanks
AndrewRoss:
Be careful buying a large external HDD to back up your PS3. If you are backing up your ps3 HDD you need to remember that any external device has to be fat formatted and as such windows puts a 32GB max (or thereabouts as far as I know) on the HDD size. If its NTFS format your PS3 wont recognise it and you won't be able to perform a full-system back-up. Also if your 40GB HDD is full the 32GB max is not going to be enough. There are ways around the limit, but I can't say if they work or not - look on google. I put all my games saves on a 2GB CompactFlash card (I had 60GB system). All demos, and paid for DLC can be re-downloaded via PSN. DLC except things like Warhawk and full games etc, can be activated on upto 5 different PS3 systems legally using the same PSN id login. Hope this helps.
Surely that can't be right otherwise how would you connect an external drive bigger than 32gb to your ps3 or maybe I am mis-reading what you are saying?