They would both be on the same bus. ATA/133 partly maxes out because of the PCI bus. Also, SATA seems to be more CPU friendly than PATA. I have such a card and I am not sure if I want to sell it or hang onto it. I haven't used it in a while, but if I ever get another G4 tower, I would want it. It's a Sonnet Tempo/SATA PCI card (32-bit/33Mhz/66Mhz) and it absolutely rocks. It also gets around the 128GB IDE limit. It also greatly increases the bandwidth of the HDD speed on the early powermacs (xxxx series and early G3s)

So a SATA could would not only make getting drives cheaper, but easier to get larger drives. I have used a 1TB HDD on Power Macintosh 7500/8600/9500 (all those) and they work great under OS 9