What brand of external hard drive with Firewire 800 will work on my power G5?

I want to buy an external hard drive to backup my files and install older software. Any one knows what is the right brand for my power G5? I google and see that some brand just does not work. If you know, please help. My power G5 is a dual 2 GHz with 2 GB sdram. I am looking for the external hard drive with firewire and usb. thank you very much for your help.