New MacBook and Portable USB HDD

I have read through all of the recent threads on external HDD's and have not seen a complete answer to the issue about power and USB HDDs when attached to a MacBook. I have found a few comments about situations where the laptop could not power an attached external HDD. I want to use portable (no power supply needed) USB or Firewire connected, 250 Gb to 320Gb HDD to support Time Machine, and other data storage.
The questions are:
Will a (new - 10.5 ) MacBook (Black) provide sufficent USB power to drive the current offerings of USB portable HDD's?
Are there specific HDD(portable) brands that work well with this smaller laptop?

My sister has a lower model (2.0 Ghz) macbook (white) and her external 250 gb usb powered hd hasn't had any problems.

WD Passport 320 GB works perfectly on macbook pro, 2.16ghz C2D 15"

Might want to check out drives with firewire too. Because firewire supplies more voltage than USB no power supply is required.