Dre plays his drums live himself and then samples them and hooks them up to his liking (source: inaugural issue of Scratch Magazine)

Neptunes, Pharrell uses the drums on the keyboards or the ones Chad put on a hard drive for him to use (source: MTV article about Pharrell's album) and sometimes live sounds (source: Remix Magazine article w/ Neptunes), Chad hooks up the sounds on the keyboards, modules, ..., and he samples (he used to be a DJ) (source: Remix Magazine article w/ Neptunes)

Timbaland plays his drums live and tweaks them (source: Making the Band 3 episode showing him making the Danity Kane song - Right Now) as well as sampling (you can hear breakbeats he's used like the drums in Fabolous - Right Now & Later On for instance, coincidence that I used to 'Right Now' songs lol),he also has a lot of VSTi synth plug-ins on the computer (source: Remix magazine article with him, Missy & Jimmy D)

Kanye uses sampled drums (source: you can hear it if you know your breaks and old records, but he talks about it in different articles, and "sample disks", like the one he tried to copy from Eminem, usually means a producer's personal collection of drums they put together, like when you make your own presets)