Ok,in the order you asked...
1)Nope,no OS will be needed
2)Yes,Your 80GB will need to be set to master (it should already be set as master) and the 160 will need to be set as slave
3)Enter your bios after you install the drive and boot back up,the 80 gig should be recoginized as primary master and the 160 gig as primary slave.
Now here's a tip on your cables..
Primary IDE aka IDE 0
The cable should start from the motherboard then connect to the slave drive (160 gig) using the
middle connector on the cable.From the middle,it should go to the master drive (80 gig) connecting on the
end of the cable.
Secondary IDE aka IDE 1
The cable should start from the motherboard and connect to the cdrom using the end of the cable
IF there are no other drives installed.
If you have 2 cdroms then use the same instructions listed above for a master/slave configuration.
That should have you up and running
