The limiting factor regarding Internet connection is the ISP's ADSL rate. Your computer can talk to the wireless router at whatever speed you like; however, the router will only talk to the Internet at the ADSL rate you're contracted to.
My Internet connection is shared between 2 wireless-enabled laptop computers, both talk to the modem/router by 802.11b connection at up to 11 Mbps. However, the ISP only provides a 1 Mbps ADSL Internet connection.
I haven't bothered to network the 2 computers as any files are transferred/archived to the back-up using a USB stick.