Problem with Guitar tracks pro 3

Hi, could anyone help me please, I used run Guitar Track Pro 2 along with Line 6 Guitar port on Windows XP for a number of years without any problems. My old CPU packed up so bought a Dell computer of my brother in law with Vista installed. Firstly the Guitar port wouldn't install, but I've managed to get an update from Line 6, I have now updated my Guitar Pro to version 3. Guitar Pro will not recognise my Line 6, I can hear it as I have an output into a mixing desk but can't get a record level through GT3. I have tried plugging a keyboard straight into the mic input on my sound card & after much persistence managed to get a record level. Now I have track bleeding, as I can only get a record level when 'What you hear' is selected.  Please help it's driving me insane, I just want to record some tracks.