Probably too late? Found your post in a Google search, btw.
Anyway, the D75 is better of the two I believe. For one thing the D75 has ASR (image stabilisation) while the D73 has none.
Now available for £47 at Argos click here.
If you still haven't purchased I'd recommend spending a little more & going for a better brand like Canon, Fujifilm, Nikon, Panasonic, Pentax, Casio, Sony, Kodak or Olympus.