external hard drives - which one?

I've been looking on-line at a LOT of external hard drives, and am
having trouble finding reviews and other good information. I would
welcome any suggestions on making this decision, or finding good
comprehensive info.

I'm leaning towards either a LaCie or an Iomega (both are 80GB,
7200RPM). I've read many postive reviews of both, and one review
slamming the Iomega software, and another review slamming the hardward
of the LaCie.

I'm also tempted to buy one of the portable hard drives (e.g.
Wolverine, Iomega) that are much smaller (palm-pilot sized) and are
USB-powered (no AC adapter needed). For similar prices to the 80GB
normal external drives, these would be much smaller (e.g. 20/40 GB),
but I don't really need 80GB anyways.

Also, I have a few other questions I can't find answers to:

1) Which drive comes with the best backup software? Or is there good
freeware (or cheap software) that would be better?

2) How much slower would a 5400 RPM drive be? Would it even make a
difference if I'm only using it for occasional (weekly) backups?

3) Is there any disadvantage to the portable/ultraportable drives?
Any reason not to get a USB-powered drive (other than that you get
fewer GB/$ and fewer RPM/$).