Payment system with hold option

Hi,

What on-line payment system would you choose for the following
situation:

my web-site intermediates payments between client Anna and client Bob.
These two clients have a contract. Anna is paying Bob for something.
When Bob starts to do what he has to do, my website charges Anna's
credit card. If he does the job right my site will transfer the money
into Bob's account. If he does not do the job, I'll have to return the
money to Anna.

Can Google Checkout do this? Probably PayPal can.

Thanks.

What on-line payment system would you choose for the following
situation:

All of them should be able too.. what you're looking for is "authorize"
and "capture".

You authorize the charge, which "reserves" it for you and gives you a
transaction code. Then later you capture that transaction to "commit it".

Be sure to look into the rules regarding how long you can authorize
without capturing.

Is "authorize without capturing" avaiable both in PayPal and Google
Checkout?