Soundfonts

Hi there,

I'm not very impressed by the sounds of Musescore.
It's understandable, since it is a notation-program, but still I'm looking to get better brass, bass, guitar etc.
Is it necessary for me to buy a (very expensive) keyboard with better sounds, or does anyone know any downloads that are compatible with Musescore?
Glad to hear from you.

Thanx
Frans