"President Bush has chosen to use the Resolute desk, which was made from the timbers of H.M.S. Resolute, an abandoned British ship discovered by an American vessel and returned to the Queen of England as a token of friendship and goodwill. When the ship was retired, Queen Victoria commissioned the desk and presented to President Rutherford B. Hayes in 1880.
The desk has twice been modified from the original 1880 version. President Franklin D. Roosevelt requested that the kneehole be fitted with a panel carved with the Presidential coat-of-arms, but he did not live to see it installed in 1945. President Ronald Reagan requested it be raised on a 2" base to accommodate his 6'2" frame.
Every president since Hayes, except Presidents Johnson, Nixon and Ford, has used the Resolute desk. The desk was made famous by a photograph of President John F. Kennedy at work while his son, John Jr., peeked out from behind the kneehole panel."
The above information straigght off the official White House website.