Red_Avatar: I believe I know what the game is you're talking about. It involved giant ants and a lot of creatures:
http://www.mobygames.com/game/world-of-aden-entomorph-plague-of-the-darkfall Entomorph.
THANK YOU THANK YOU THANK YOU
I had seen that name before and just disregarded it. The screenshots didn't look right, but I guess that was just my poor memory because then I found this:
http://www.youtube.com/watch?v=lZcdm-p3yQs And that is definitely the music I remember (amazing music for a game at the time I thought), and this:
http://www.youtube.com/watch?v=_bJ52c7tIhc I remember that but now, but I guess I never got very far into the game and didn't realise what a role bugs played in the game.
Thanks again, and thank you everyone for trying