Hi,
I'm always working with CyberSource for all my credit card
needs and that works well.
But you would not be able to get that setup by end of the
week (as well as most other services), because it usually takes
already several weeks to get a merchant account (the online
representation of the company and bank account).
So you probably have to look into a hosted service that
includes that. don't have a recommendation for that, sorry.
cheers,
fober