I recently got the G4 in my sig and I'm in the process of upgrading it. I plan on using it as replacemnet to my desktop PC since the PC isn't cost effective to upgrade.(I'd have to gut the thing for it to be worth while) I've figured everything out but the HD options. It still has the original 30 Gig ATA drive but I will need more space. I have research the whole 12X Gig limitation on my system and the options for PCI card expansion. My question comes down to either ATA or SATA. I plan on using it for primarily web, e-mail, itunes backup, downloading and storing torrents, and watching DVD's/videos. I would also be using it for backup storage for my Macbook as I'm planing on doing some video editing with it down the road. I guess I could get away with just adding a slave 120 Gig drive, but is that the best performance wise? Would spending the extra $ on a SATA card and multi 200+ Gig drives be worth it? Would the OSX run better on a larger drive then use the 30 Gig drive as a backup "mirror" to it, or leave it on the ATA drive and set up the others in some RAID type of configuration? What I'm looking for is someone who has used ATA and SATA drives in similar system and what their performance was. Is the speed differance noticeable or worth it on an older system like this? Any advice would be helpful, thanks.