I might be way off on this, but I believe the original poster said that he was just recently "registered". I'm not positive what that means in Colorado, but I'm guessing that it means that he's just starting in the appraisal training process?
If so, I'd suggest that he NOT buy a new, big, go fast computer system until he finds a licensed or certified appraiser to train him. If he'd like something to start on until finding that mentor, I'd suggest a cheap used IBM compatible (are they still called IBM comp?) computer with a cd-rom drive and a couple gigabyte hard drive, with Windows 98 already installed. These can be had with monitor, keyboard, and mouse, for under $100, usually listed in your local newspaper's classified ads. You can go to some of the appraisal software company websites and either download a 30 day trial or order a free demo cd to play around with the software.
Upon finding your mentor, he/she's already going to have a computer, operating system, and appraisal software package that he uses on a daily basis. Get the same type computer (or compatible), operating system, and appraisal software. Actually, I wouldn't be surprised if he/she has an older system with all of the stuff already installed that he/she would be willing to give/lend you.
If the poster is actually already licensed/certified or has entirely too much money, please disregard my whole message as inane ramblings.