I forgot my mac password so can't update software, etc. Everything I've read says to reboot with the install disk and holding down "C", but that has no effect. I've also tried holding down "alt" and holding down "command" and "s" per some other ideas but nothing works. It just reboots as normal so there's no opportunity to access whatever special menu they keep talking about.
Aha! Swapping the keyboard did help. I can now do the C reboot trick. I tried following the instructions to reset the admin password which didn't quite work as described, but I eventually got it to work. Here's some info on what I learned which may be helpful to others:
The instructions told me to boot with install disk 1 and then choose my hard drive when I got to the 'reset password' step. That didn't work because I couldn't choose my hard drive at that point. The only option was to try to reset the root password on the install disk itself, which wasn't possible.
Eventually I switched to booting with the Snow Leopard install disk instead and that worked. I was able to reset the admin password, but then got prompted to reset the "keychain password", which I couldn't do without knowing the old password. But it didn't seem to matter and I just reset the keychain.
Hooray, I can finally update software and get some long overdue security updates.Thanks to everyone for your help here.