As ChrisA mentioned, the Spyder2 will assist greatly.
In the story you told about Moab, PP on a PowerBook, and looking washed out on your desktop (PowerMac G4) - you were really putting your PP skills to the test. Calibrating your monitor, is very much like calibrating your white balance in the camera prior to capturing an image. What looks to be acceptable under 5000K, will look totally different under 3200K, or 6500K. When you calibrate a monitor (or camera WB), you're calibrating the device under certain ambient lighting conditions - to be used only in those lighting conditions.
That said, every display will very color renditions (even the same make/model) under the same lighting conditions. (My two 20" ACD's sitting side by side on the desk very slightly when calibrated using the same puck, and software.) Unless your color management software allows for "matching monitor profiles" in a work group environment - there will always be some deviation between your monitors.
If you were performing the PP on your PowerBook in a different lighting environment than is used in your home - I would expect there to be some varying differences. (Looking over saturated, or muddy would expected - especially if neither monitor were calibrated to their environment.)
Besides calibrating your monitors, you should also be calibrating your device input (camera, scanner, etc.), as well as the printer to paper/ink you plan to use for any given image. When using a 3rd party printing service - most require that the image be sent to them in a CMYK profile. (Depending on your needs {how a**l you are about color reproduction} you will want the printing service to provide you with the color profile they will be using.) Digital Photo Pro's web site has a couple of great articles on "Crushing CMYK" and "Curving RGB Color"
http://www.digitalphotopro.com/tech/curving-rgb-color.html.
Both of these articles will go a long way in helping you work through color management, and creating an image that will display as closely to what you see on your monitor in other arenas - print, web, etc. The best way to work through this is to do what you're doing now, and maybe look into assisting working photographers in your area to see how they incorporate icc profiling into their workflow. Lastly, calibrating your monitor/printer is not a one time affair, and some of the better software programs out there will assist in creating a schedule to remind you when you need to re-calibrate / evaluate and edit your calibration curves.
HTH's,
Art
