This is rapidly becoming pretty one sided. I agree that the ROS is the one to buy first--and possible only. Unless you are going to do serious stock removal, you probably don't need the belt sander. I have both a 3x21 and a 4x24 Makita. They are great sanders but I never use them. They have become expensive dust magnets. I have the older Porter Cable ROS, 5" and I am very happy with it. It can sand down fairly serious surface flaws using 80 or 100 grit and continue to an extremely fine finish at 220 or higher. Good Luck.
+1 on ROS first.
If going with a 5" ROS make sure to get one with 8 holes and not 5. The extra holes remove more dust so the sander does a better and faster job as well as the sand paper lasting longer. Both the PC and Rigid have gotten good reviews.
David, You made the correct purchase and will soon be glad you did.
James