I just bought a PowerMac G5 dual 2Ghz with 2gigs of RAM. My only problem is that there's only 160gig of HHD. I think it's not enough! I had an external 120Gig HHD for my PC and I tough it will work on my mac but it seems like I can't write on it. I can read, copy file from the HDD and paste them on my Mac but I can paste stuff on it! So should I buy an external hard disk for mac ow buy an internal? How much gig?