There is another way other than software-hacking or installing PCI-cards! Apple reports
I know this thread is old, but maybe this additional info will help someone searching for it later, so I would like to share a link with you:
http://support.apple.com/kb/HT2544?viewlocale=en_US
I am German and I do not know whether I have understood everything under this link, but as far as I got it, it says:
There are to ways:
1. you have a mac that allready supports drives larger than 128GB (or 137GB respectively), which is Macs from until June 2002. (Beware there are some Quicksilver Models that do support it and some don't, due to Apple using other parts in one model it seems.)
2. If not:
a) install an OS X, higher than 10.2 and you can utilize a bigger harddrive
b) For OS 9 Users, they should use OS 9.2.2 and make partitions of not more than 200GB each. (Example, if you have a 320GB HDD make one with 200GB and one with 120GB)
(if you have lets say OS 9.2.1 installed and use a 160GB HDD it will use the drive, but somewhen it will write out of the 128GB space and the drive will get problems. (concerning the last point I got an answer from hitachi, they confirmed that the computer will somewhen start writing in places over the 128GB and will get problems including not booting, corrupted data). You will not notice that in the beginning of use.