Well, If your neighbor is unaware of your "leeching", it's wrong and would get you a black eye and a broken rib, would that neighbor in question be me.
However, 2 of my neighbors share my connection, with my permission and a small fee. Each gets 1 meg down for $5 (they don't need or want more) and both have secure, password connections thru my wireless router. Only rule is no morpheus or kazaa.
My point is, you'd be suprized how many reasonable people actually exist. If you ask your neighbor, he might agree to a similar arrangement thus canceling out your moral dilema.
However, if you're screwing over your cable/DSL company out of profit and contol, you have a beer on me anytime
*edit*
NVM, just re-read your post.
Go for it...it's not coming out of anyones pocket.