Oh great and wise internet

[stellar_muddle]

The time has come to get a new portable hard drive.
I'd provide the links to Dick Smith (it is within easy walking/bus distance) but the direct links to products seem to be failing/ getting redirected.

So:
SEAGATE FreeAgent 500GB External Hard Drive (if that link works)
$189
Sod all technical details bar the size.
Seagate FreeAgent PRO 500GB External Hard Drive
$209
"USB and eSATA" - so what does the later mean and is it worth paying the extra for?

Other suggestions I have had are:

(case)
and

(500Gb Hard drive) for total of $185.14 plus a bit more of a hassle ordering and assembling...

Suggestions?