Hi, this is an old article, but read the last section of it on MIDI sounds http://musicmall.com/cmp/article6.htm, that is your issue.
As a fix, try one of the sound cards from here http://www.google.com/search?q=laptop+midi+sound+card&rls=com.microsoft:en-us&ie=UTF-8&oe=UTF-8&startIndex=&startPage=1, one of them should do the trick, just need to pick out out based on what you can spend for it. Looks like a good MIDI-capable sound card is about $150