Looks like the 6+1 live also qualifies for the rainbow six code:
https://www.bestbuy.com/site/microsoft-xbox-live-6-1-month-gold-membership/4743300.p?skuId=4743300
Saw this posted on a gamefaqs post... Not taking credit - just sharing what i saw... i've tried it already and got my code in a few minutes.
promo code: XboxEMWAjn7fbddo3
http://www.microsoftstore.com/store/msusa/en_US/pdp/productID.255252000
http://www.amazon.com/gp/feature.html?ie=UTF8&docId=1000296831
then click [Enter your code] and it will show what you have. At least, that's the only one i know of.
360
power brick + cord
some type of tv hookup (hdmi cable won't work though, i don't think)
basically, everything that will allow the unit to function. hard drive is not required, but can be traded in as a separate item.