Thank you all for the information guys.
Sorry for the delayed reply...
Since soundfonts was not what I needed I went with Ben's suggestion.
http://theremin.music.uiowa.edu/MIS.html
The recording could be better, I guess I should be thankful being able to have these for free though!
After trimming the samples, total size is reduced to about 320 MB which will be just fine with my 1 GB memory (hopefully..)
Thanks again, have fun!