I am a big Mac fan too and I would love to use a Mac at work. In your case - have you also considered buying software in your costs? Does the business already have software for the PC - in that case - you will have a very tough time convincing your bosses/clients why they should shell out the $2229 + for the 2.8Ghz Extreme and then turn around and buy software - (Adobe can cost at least $900 and up for a package) which puts the price above the comparable Dell.

You also mentioned that you are not an IT person. Well - is there an IT person that knows enough about setting up a Mac in a mixed environment and also has some Unix knowledge? If this is a small shop - then it won't matter since they probably rely on the vendor (Dell, HP Apple) for support. You may also need to consider what that will cost as well.

Sure - Macs are better than Windows for what you are doing - but don't forget - someone else is paying for it - and a lot of times they tend to be very short-sighted about costs.

Good luck!