I need to format a new hard drive to install tiger. What is a program that I can use to do this for free? Also do you ever partition a drive into two sections for scratch disks in photoshop, or is this not needed?
The Tiger installer has Disk Utility in the menu. It will format and/or partition drives for you. I've partitioned a disk to keep video data separate, but I haven't seen the need to do so for Photoshop. The advantage might be that you keep all the "junk" separate and your main disk is less fragmented, but the disadvantage is that you have to decide up front how much space to allocate to a separate partition. Too big and you've needlessly cramped your main disk. Too small and your scratch files won't all fit there. Either way, it probably won't make a big difference in your performance.
You don't need to use a separate program to reformat before installing Tiger. Just simply stick in the install DVD and select "Clean Install" from the list of install options. Then it'll just wipe your hard drive and give you a clean system.
What if I have two hard drives, one connected by usb that is unformatted. Could I install tiger on the secondary hard drive?