Can You Help Me w/Clipart License Agreements?

I am designing animated and static greeting cards for use on the internet. To do this, I am using two sources of clipart/photo stock CD collections as a part of the designs I create. These sources are PhotoDisc and Nova Development Corporation. My cards will be either stored on the server of the company who buys my designs for use as greeting cards, or perhaps sold on a CD as internet greeting cards designed by me. (They will be created in several languages, to be used as greetings world wide, in connection with a greeting card software program being sold by another party.) The cards are not to be downloaded or copied by greeting card users. However, we cannot truly prevent anyone from copying anything on the internet.
I have tried to contact both PhotoDisc (via phone) and Nova (via E-mail) regarding my questions about the allowable use of their clipart in this particular way, and neither company will give me any kind of answers to these questions, and they tell me to see a lawyer. I cannot believe that they are unwilling to help me define what they feel is proper usage of their product. I feel like they are trying to set me up to break the law, and then they can sue me. How on earth can anyone get a reliable answer about their License Agreements? Their agreements even mention using their images for designing nearly anything for the internet, and also the mention of greeting cards is listed under what they say is allowed usage. But, it is rather unclear, and I want to be sure. Please help!!
(I am in Arizona, but my work will be published on the internet for use worldwide.)

Thanks so much!