Better graphic cards only allow the image to move faster. If you are not going to do anything but look the Mini will do find. In fact the mini is OK for light Photoshop users and even some video work. The current mini is a dual core processor with up to 4GB of RAM. Beter specs than most PCs Only the disk is not really fast.
You can put more in but it will only address up to 3.3GB ish. Just buy it stock and shove more in if you're keen on tampering with stuff. Otherwise, 2GB may do. I use mine with 1, but it's a bit of a drag with aperture.