Im I Being Scammed? And If I Am, Tell Me How?

I'm selling my 30gb Zune for 110.00 on Craigslist and within 16 hours i get 2 leads. i responded to a person named Mark Dennis. He never told me where he lives. He just wanted me to ship it to his cousins house where he's stationed in Nigeria. I thought this was a scam from the beginning, but then i looked up the address he gave me on Google Earth and it looks pretty legit. He sent the money to me using Paypal already. Please answer ASAP!