Access Point..

Moving soon and the only way I get an internet connection is from the buildings wireless. I have a few computers and an Xbox 360 which I would like to have on a LAN. I believe they will grant access to the wireless by MAC filtering or some key. If I got an access point and gave them the MAC address of it, can the AP connect to their network with user/pass and provide me with my own wired LAN with dhcp/nat?

Sorry if this is a stupid question, not up to scratch on wireless.

Yeah, you just need to give them the mac address of the wireless router and all will be good. I had to do this at my apartment complex when they had mac address filtering in place.

You need a Wireless router capable of functioning as a "Bridge" A Wrt54gl with ddwrt is probably going to be your best bet.

Useful links:
http://www.newegg.com/Product/Product.aspx?Item=N82E16833124190
http://www.dd-wrt.com/
http://www.dd-wrt.com/wiki/index.php/Linksys_WRT54G/GL/GS/GX#WRT54GL