Sound Effects

I found a very good site for getting sound effects http://www.grsites.com/archive/sounds/ which pretty much has most of the sounds I would need. However I haven't decided yet whether I will use sound effects because I have a lot of parts where a sound effect could be applied mixed with the music it might get a bit too much and sound messy. Saying that though if I watch my animation back with just the music a decided it needs sound effects I will look back on the issue.