which external backup drive for macbook4,1

[Citydweller]

OK, I've had my 13.3 Macbook since April 2008 and the only device connected to it is a Ruckus broadband gateway to access the internet via ethernet. I know, yawn.

Currently have Mac OS X 10.5.7 and decided I gotta download Windows 7 RC (because I can) but want to get an external hard drive to back up my laptop first.
HD = 250 GB.
Has a firewire 400 port

For an external HD, I considered
WD My Passport Essential 500 Gb, but after reading through the forums,
it sounds like the USB connection will
a. slow everything down/ suck too much power?
b. Is getting an external hard drive with firewire preferable, critical?
c. How important is having a hard drive with it's own power source?


Will initially use Time Machine
Portability is NOT a factor

Not-networked, not a gamer, will be working from home a lot more (OS X & Windows) Plan on using bootcamp till I find a need for Parallels, vm fusion
Will be downloading maps, geocaching stuff

Any advice on most critical features, not necessarily specific brand names for an external HD to back up a laptop?

[eXan]

FireWire is preferable because of higher transfer speeds and lower CPU usage, but it also comes at higher cost, especially the 800 Mbit version.

If you don't need your external on the go with you and plan to use it just for backups (no need for speed), I suggest you get a desktop (3.5") USB external.

I hear WD MyBooks are good and they have quite a few models to choose from - http://www.wdc.com/en/products/index.asp?cat=8