Sound Options for my Videos

I'm someone who usually leaves the sound component till the last moment, but I've been thinking about sound for a while now, convinced that I need to have music backing my video sequences.  Thus, I've been familiarising myself with a DS program called Rytmik (by Cinemax), avoiding the likes of GarageBand.

I met with Alistair today and he suggested, based on the vague description I have, that I instead use the sounds from the environment, citing Blow Up as an example of such a thing.

Alistair did back up David's advice that if I did want some music that GarageBand could be useful - only to remember to avoid the guitar and piano loops as they are quite recognisable.