Be sure and upgrade your hard drive(s) because by the time you get those 21 MP images uploaded and converted they will be 80 MP files. So every 125 images will eat up a Gigabyte of disk space.
If you figure you'll just make 'em jpegs to make the files smaller, don't upgrade, because you'll be throwing out 75% of what you upgraded for.
Do not get caught up in the megapixel war. Seriously man. If you are going to ask a question like this, give us some details. I asked about your objectives for the upgrade. Why are you wanting to upgrade? What do you want to gain?
There are plenty of really good people here and they will help you. You just have to give enough info.