Im currently using a wireless card to get the net from my landlord's router upstairs. Is it possible to then send this connection out through my ethernet port on my pc and into my xbox 360 and share the connection?
You can share the connection via a cross-over just like fihart says. I've actually done this before with a Laptop + an XBOX. There are a lot of write-ups and very good how-to's online. You basically bridge your Wireless/Wired connection and then share the Wired connection.