Thanks for the info.
I *did* search the forum, but apparently I didn't use the right keywords, as all I found was some jargon and some stuff you got to pay for.
I tried to add the sfz as an effectto a track but I can't find it from the list. I copied the dll to the directory like you said and then started the Reaper... I'm also quite lost of that MIDI item you mentioned.. :P
[edit]
okay, appeared after couple program restarts. Will try to figure the rest out