I'm not talking about the end-credits music, but that nice Christmassy music that was being played as the Doctor was choosing his clothes, and the Tyler family (+Rickey boy) having Christmas Dinner.

I absolutely loved the music - it ranks in my top 20 Christmas Songs!

But does anyone know if this was an existing song re-made for Doctor Who, or did they make it especially for the show?

it is specially composed for the show... it's sort of the Doctor and Rose theme if you like - if you go back over the first series, it's played frequently during especially poignant moments... most notably the end of "the end of the world" and the end of "the parting of the ways".... but yes - specially composed it is.

Apparently, the 1960's-feel music that the Doctor got changed to in the Tardis wardrobe was specially written by Murray Gold for the episode.

Here's a link to an excerpt of the song

I dont recall hearing that melody in series one! I must play the episode again and listen carefully...

The song is called 'Song For Ten' (meaning Doctor No.10)

He was mistaken and thought the music the question was referring to was the music over the final scene in the episode, where the Doctor and Rose stand in the falling ash deciding where to go next.