Oh, please. My old hardware is so old that it can't even run Windows 1.0 (Tandy 1400 LT).
Anyway, that is NOT the best way to try linux. Best way is definitely on newer hardware that isn't apple branded.
Anyway, that got me to the point where I could see my desktop after I logged in. Maybe this won't happen to you, but my Mac had a problem at first where the backlight turned off once I logged in. But I went back to a tty (ctrl-alt-F1 or F2 or one of those), logged in, and typed
It may have been mate-power-manager, instead. I don't remember.
Anyway, I then switched back to the X server (ctrl-alt-F7 on my computer, yours may vary), and the power manager settings were there. I turned up the brightness and suddenly the screen turned on.
Alternatively, you may be able to use this, but I haven't tried yet:
Anyway, you may not encounter that issue at all - I had transferred my old /home partition from my laptop's debian install.
Now I needed a wireless driver - my iMac used the BCM4311, you can check what yours uses in lsmod. I noticed that I had no network managing software, and wicd wasn't on the DVD, so I went with network-manager.
apt-get install network-manager-gnome
I ended up switching to an external USB because it somehow got better reception when I clipped it to a tomato juice can cantenna.
In any case, download your drivers, following whatever instructions from another computer.
For the BCM43xx series, downloadhttp://www.lwfinger.com/b43-firmware/no_net_install_bcm43xx_firmware.tar.bz2
You may also need https://packages.debian.org/sid/b43-fwcutter
Wow, the captcha's a technology related word! 'eprom'