how to get background music for "We run this" by missy elliot?

i LOVE the background music/beat of "We run this" by missy elliot and
i really wanna download it onto my IPod Nano...what site should i
download it from. I tried beemp3.com to no luck...if you have any
other safe and legal sites, please tell me!!
i want the background music only, NOT the actual song :)
thanks :D