Your current Xbox 360 drive drive will not be compatible with the new 250GB Xbox 360 slim, Microsoft has confirmed.
To transfer your data over to the new console you'll need to go through the rigmarole of buying a Data Storage and Transfer adaptor, and port everything over.
Not ideal, but put it this way - the money you save on not having to buy one of those over-priced Wi-Fi adaptors (Wi-Fi comes integrated into the new machine) can be spent on the data adaptor.
The spec sheet also touts the new Xbox as the 'only console with 802.11n Wi-Fi' - that being the fastest standard of Wi-Fi today.
But as reported yesterday, we're told Sony has a new 500GB PS3 SKU on the way that boasts the same Wi-Fi (and bundled with PS Move). We'll see this week.