Well take at look over at xda-developers.com For the 1st gen HTC devices there's an developer unlock available. If you need any further information, just say anything
You got the first generation WP7 (HTC HD7) The second generation WP7 are the Radar and Titan (the phone that shipped with Mango OS (7.5)) Hope this helps! @Topic You need to unlock your phone (full-unlock, dev-unlock, interop-unlock or chev-unlock) to deploy homebrew apps!