Help With Taking Online Contributions

I am the web developer for a Democratic Party county web site in Arizona. I am tasked with adding functionality that allows us to take online credit card contributions.

At this point, I have decided against setting up a merchant account in favor of using a third party service. The one I am considering is http://digitaldonation.net. Is anyone familiar with them or have some other recommendation? Do you have any other advice on this issue?

Thanks!