If there is any utility left in your old Mac, sell it and use the money to buy a cheap x86 box.
You can get a very nice Dell box for $250 right now via Dell Small Business. That's with a modern dual core processor, 512MB of ECC RAM, 80GB SATA, CDROM, GigE, and a 1 year warranty.
The Dell will be a lot more pleasure to use for Astaro or any other Linux endeavor vs. an old Mac.
