I have a 24 inch dell monitor and im thinking of switching over to mac. what are the options with the info bel

so i want to keep the 24 inch dell 2407 monitor that i run now. im trying to decide between a 24 inch imac, and then adding the dell monitor or a mac mini. the question is based on not wanting two different calibrations on the two different monitors if i go the imac route. this is very important to me as i process photos and i only print large prints, which are costly if not right within the first two. this brings me to another part of the question. can the new 2.0 mac mini run photoshop cs3 at a high enough speed to not make me ......frustrated. and if i go the imac route, can i adjust the monitors independently? i know that with the imac way i get a whole bunch of viewable work area, and it would be great, but i also know that the mac mini would be less of a cost with more than enough monitor (24) to go around. thanks