Don't have any experience with the Colorado, but keep in mind that with Garmin, the software goes with the unit.

Once the software is linked to a particular unit, they go together. Lose the unit, the software can not be loaded on another GPS. Gone, voila, useless DVD. I know this works for software that has to be "unlocked". Don't know for sure that this applies to the topo software (forgot if my topo software is linked to my 60csx)

And if you buy the software on the unit or on a SD card, those maps can not be loaded onto your computer for better viewing. They stay on the unit/SD card. The SD card can be moved from unit to unit though.

Check out the groundspeak forums for more info.

Note: this thread should probably be moved to the electronics forum.
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Steve