We are the least techy household ever. Ds (5) loves dancing and singing. We have taken the leap and bought a second-hand wii which comes with many games, including the sing-along/dancey things. I am told by all who know him (and Wii) that ds will love them 
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So I am guessing the dance-mat thingy that has been on my Amazon wish-list for months is now redundant? He will also be getting a paper jamz mic (already bought) and an mp3 player to go with it. I imagine that is really enough for the dancey things? Though dancing is his passion...
I have got to the stage where I really don't know what to think, never having seen any of these products in action, and just want to be done!