I have to disagree with quite alot of you here......i would say in this case its better to keep the services under the same roof.

My reasons being.....you only have one website to market. Design and hosting go preety well together, if someone is buying a webdesign from you..chances are they might need some hosting to?

Look at my website banners2go.....i sell banners and i also offer targeted traffic, the two services go hand in hand. I could have made a new site etc but it would mean i would have to advertise that as well.

My thoughts....