How to allocate 10 days to these places?

With only 10 days, that's pretty good, but you might want to take one day off of paris and take it in luxenburg. Just remember that even if you spent a week in each place you wouldn't see everything.

You should probably cut Luxembourg this time as it's too far out of the way for such a short stop. Train travel costs more than coach, but the time you save is worth it. Add your half day saved to Brussels. Paris Disneyland? The rest looks good.

I agree with Luke but from Brussels I'd take the one hour train ride to Bruges for a day--truly one of the most gorgeous medieval towns in Europe--be sure and take a canal ride there too. See Rick's book. Forget Disneyland when there is so much of the real Europe to see.

Your itenerary looks pretty good to me.

If you are so inclined don't forget to stop by a couple of the coffeeshops in Amsterdam. I suggest Tweede Kamer, Barney's Breakfast Bar, Paradox and Rokerij. But only if you are so inclined.

Have fun!

In Paris, instead of Disney, consider a short train trip to Versailles or Chartres (loveley town & cathedral). In Amsterdam, don't forget about the Van Gogh Museum and Rijksmuseum--awesome. Take a short train ride outside of the city to Edam or Volendam--ride a bike on top of the dikes, see the windmills and cheese factory like you said. I haven't spent time in Brussels. Since you are going to several larger cities, Brugges would be a nice change--it's quaint & charming. Not so overwhelming but still lots to do and see. Maybe spend 2 days there. Not sure about Luxembourg--never been. I believe your itinerary is very realistic & sounds like fun. Just make sure you get out into the smaller towns/countryside. The large cities have their treasures that are "must sees" but the countryside has the ambiance and charm.

Definitely skip Paris disneyand - NOT worth it..too many other things.
In Paris, see Ile de la Cite, Notre Dame, Musee D'Orsay (I like this one better than the Louvre), the Louvre (but have a game plan before you get there), Versailles, and of course, the Eiffel tower, so you can say you've been there, champs elysees and Arc de Triomphe... Chartres would also be great if you can get there.

This is a personal preference, but I'd skip Brussels and use the time to see more of France - Normandy, the Loire Valley, or Provence.