Congrats on the Galaxy Tab.
My choice, if I was in your boots, would be to hang onto the Kindle a little bit longer. I can't imagine selling my Kindle and it lives happily with my IPad. I don't use my IPad much - I prefer my Kindle - but no way I would sell it as it is there for a rainy day. I also know that as soon as I get rid of something I will decide I really loved it and have to replace it. I did that with a freezer and yes, I know that a freezer is not really as attractive
Good luck with your decision however you choose.