Hi Stephanie,
Perhaps someone will come up with some better info for you, but in the meantime, check out GCU Wiki's info on Clip Art. (I'm posting an excerpt, below.) As for Photoshop in particular, I believe that when you purchase the program, with the proper license, you may use whatever it includes. I may be wrong; I'm no expert on these things. It would best for you to go back to your own Photoshop program and read the licensing agreement. I know that if I purchase a Clip Art package, I may use it in whatever way I wish. I assume it's the same for Photoshop. Check, just to be sure.
 
5. CLIPART - Most clipart, backgrounds, and textures found on the internet and even included in graphics programs are not licensed for commercial use, which includes your GCU greeting card. PLEASE AVOID USE OF CLIPART or any artistic item that you have not created or do not have the rights to use. You place yourself and GCU in legal jeopardy. Here is the description in the GCU terms and conditions that you need to be aware of:
 
General Notice to All Artists - Your Image Responsibilities - By submitting this image you, the Artist, represent to have complete rights or permission to use/sell this image. It is your responsibility to insure that this image does not infringe on the copyright, trademark, patent, trade secret, trade dress, right of publicity or other legal right of any third party. GCUniverse reviews cards for image quality and appropriateness. GCUniverse does not research nor decide upon legal rights of Artists' images.  
 
In respect to clip art, stock and royalty free images, it is your responsibility to insure that you have the proper permission or license for commercial use of the image in this manner, for resale on paper greeting cards.
 
 As in the T&C's, GCUniverse does not tolerate the copying of another artist's creative work, which includes art, image and verse. If it's not your idea, artwork, or unique verse, don't use it. GCUniverse reserves the right to terminate an artist who violates these conditions from using our site and services.