I took the 32gb card from my Droid X and put it right in the RAZR. The only thing you may want to do (though not necessary from what I can tell) is delete any program files you have on there because they will be recreated when you install that app on the RAZR.
Going from Motorola to Motorola might be different, though. I'm able to see all pictures from my Droid X (as well as new ones from RAZR) in the gallery on the new phone. However, if HTC doesn't use a "dcim" folder to house the pictures, this would be different.