It is a consumer level product, he was right about that. Not to be a wise guy, but that's why the towers are called Pro's.

Try this link. It appears you don't have the 6 bit display from the previous model, it is a good display, but maybe not consistent enough for pro color correction.

I recommend to my customers if you're doing serious color or Graphics work, you'd be better off going for the pro line, a tower and a good monitor, or if you can't afford that and have the desk space, get a good external monitor for the iMac. You'll have plenty of screen space and a monitor to do your proofing on. The video isn't quite as robust in the iMacs as the MacPro, the video "card" is the chip on the logic board, and it uses your real RAM for video memory as compared to a tower with a dedicated video card and RAM on the card. The 24" have a better choices on video cards than the one choice of the 20". The better video card would not give better color, but better performance if working with really large files. If you don't need the video muscle, the 20" iMac is a good choice.

Below is a link where a couple of our local pro users were discussing their recent acquisitions. Unless you buy an Apple 24" monitor you'll need to get a Mini DisplayPort to DVI adapter if you go that route, around $25.

Welcome to the joint BTW.