What programs can help me with designing T-Shirts??

[Ridin 4 Pac]

I'm trying to design T-shirts and instead of drawing it out on paper, I want to be able to do it on my computer, but I want a program that can help me out. Im using paint right now and its real frustrating, anything easier? I tried powerpoint but that was kinda hard too, but im not familiar with powerpoint so that may be some of my problem, anyway, anyone know any programs that I could download to help with this?

 

[Advocate]

Photoshop???