[kwlug disc.] 2.5'' enclosures run off USB power?

[Rick]

I'm thinking of getting a 2.5'' USB hard drive enclosure
to go with the 8G Eee PC that I'm going to buy.
Hopefully I will get the Eee PC early this month;
I saw it listed at ncix.com today.

I know that 3.5'' USB hard drive enclosures need
an extra power supply to operate where as, for instance,
memory-card-readers run off the USB.
So if I get this 2.5'' enclosure, do I also need to lug around
a power-supply as well? If so, then that cuts into
the benefit of the 2lb Eee PC.

My other option is to stick with smaller-capacity-but-zero-hassle SDHC.
With SHDC memory-cards, there will be a price drop every so often.
8GB is already down to $60 and I saw 16GB at ncix.com for $170.
So I'm guessing under 16GB $100 next year and I don't have
to carry an extra peripheral.

But if a compact 2.5'' enclosure _does_ run off USB
then it would be convenient enough in many situations.