what are the best things to do with kids (aged 3 and 5) in Amsterdam for a week in October?

We are in Amsterdam during the October school holiday (from 22 October to 26 October). We are staying very centrally but are planning to have a break from the car so will be using trains and trams to get around. We would like to do a mixture of things including galleries and museums etc but also want to some things that the kids will really enjoy and remember, and ideally will be things that they can't easily do at home (London). All suggestions gratefully received!

no 1 on your list should be a rondvaart( channel tour),

Well the "coffee" houses and red light district would be out.
I'd also suggest staying out of the parks they are filled with druggies and needles laying around everywhere.

How about a nice ride in the country?

You can always take them to a restaurant & get them a "pot" salad, then they will sleep & you can do what you want to ?

Go to Madurodam, a short train ride towardss the hague. Miniture city is just perfect for kids. Go to the Flower Mart, and do a canal trip. Anne Frank's house may be too much for the kids. Go see the dikes, and also nearby towns. Gouda comes to mind. Have fun

As The Hague/Den Haag is my hometown I'd love to try to talk you into coming here, but I don't think little children enjoy riding the public transport system for hours to and from... However, Madurodam is probably THE best place for kids to visit in the entire country... http://www.madurodam.com/default.php?language=1&sqlmode=1&fid=479

I'd advice you to either forget about Amsterdam altogether and come to The Hague, OR, just visit this site for Amsterdam if you MUST go there... http://www.iamsterdam.nl/visiting_exploring/special_interest/children_families

I guess small kids would not like most touristic attractions that much. Madurodam is close to Den Haag (The Hague) and is a miniature of the Netherlands. Really nice!
But you can also go to the Walibi World that is a children park (check it out at www.walibiworld.nl, then select the english language). If you go from Amsterdam to Hardewijk train station, you have a special bus service that goes there and brings you back.

You could also take them for a unique experience to the Kinderkook Cafe on Oude Zidjs Achterburgwal where children do the cooking and serve you. There is also the Artis Zoo, and the Madurodam (miniature city) is very cool too!