midi mes

Welcome to the forum!

What software are you using?
What drums are you auditioning in the browser?
You can hear SD3 sounds only if SD3 is inserted.
Have you inserted SD3 as a softsynth in a project or are you using it as standalone?
(Actually, I don't even know if SD3 can be used standalone.)

Hard to say if a codec is missing (I don't think so) without knowing anything about what you're doing.
Have you read the manual and done the tutorial about using soft synths (if you're using SD3 as a soft synth)?
I simply don't understand what WMP has got to do with SD3.

Please try to give some kind of a description of what you are trying to accomplish and how you are trying to do it.

What have you inserted where, what kind of tracks you have and what are their inputs and outputs, do you have your E-MU as the recording and playback timing master (Options dialogue), how are you feeding the MIDI (keyboard, mouse or electric drums), what drivers are you using (ASIO is the most recommendable)...

Is SD3 the one you have just left of the browser, or just for the project. There is a place just left of the folders, that should SD3 there as well, and if there are more than one synth down there, make sure SD3 is highlighted. I get the synth rack, and media browser backwards sometimes as far what is controlling what. But it should be while in Media browser, starting from left SD3, then whatever you are browsing for, and then in the final column the actual loop, or sample. Good luck!