thats exactly what i have. i use an excessive amount of photoshop and other pro-apps and it works just fine, but i would recommend CS3 so you don't have to run it under Rosetta. i use CS and its not the fastest thing in the world, but it is enough to get by.
1) 17" display is really small if you want to do any serious Photoshop work. And it doesnt matter if you;re working with 2000x1500 images or 35XXx26XX like me, because the screen's resolution is still lower.
2) 1 GB RAM on an Intel Mac is like 512 MB on a PPC Mac, especially if you're using non-native app (like Photoshop). 2gigs minimum for photography. My iMac has 1.5 GB and its really slowing down when using Aperture and especially when I have to use Aperture and Photoshop at the same time.
So I recomment at least a 20" display and with a minimum of 2 GBs RAM for photo work.