Transfer 160gb to old ps3 keeping all data intact

Ok this is going to be a long shot but im selling my ps3 due to personal reasons and i said my friend could have my 160gb to put in his ps3 and i would take his 80gb, now what were trying to do is transfer everything from his 80gb to my 160gb and keep it all working and vice versa so i can still use a 80gb drive in my 160gb machine until I actually sell mine, I have 2 external 500gb hard drives to handle the data transfer from system to system, the main worries is copyrighted saves, how would I get round all this and keep everything working but on a different hard drive.
Any ideas???
Sorry I couldnt explain it any easier

As long as the saves are going back on the same console they will work regardless of which hard drive you use. Either use the PS3 backup program or just copy all the saves to a flash drive, swap the hard drive, it will probably prompt you to format, then just copy the saves back on.