Keep in mind that developing in high DPI requires a much better computer, whereas with Illustrator you can run with a much slower processor, since vector files scale differently.
I'd recommend learning Photoshop. For the sake of card design, you can do there everything that you can with illustrator. However, it also has an extremely large amount of other features that can propel you into other types of design.
I, like Randy, cannot state Illustrator. I don't understand how it works despite working with it for years (for magazine/newspaper layouts). I'm used to having full control over any part of the image like in Photoshop. When I open a file in PS, I feel completely in control. I can open a photograph of you and turn it into an abstract space scene wallpaper. I open that photograph in Illustrator and... I can rotate it? Maybe put it next to some text?
If you're going to torrent the program, though, just go the whole nine yards and get the master suite and see which program you like more.