I've got 43GB of Doctor Who here - although that does include the episodes of the last series that I downloaded as they were broadcast. (I might actually just delete those, since we do have the DVDs...)

I don't have a lot of what most people consider 'classic' Who - Tom Baker's fourth Doctor - but I do have all of Colin Baker and Sylvester McCoy (plus the eight Doctor TV movie). Oh, and the first episode ever.