I have no experience with Alpha Shield. The firewall with XP in woefully inadequate. It only scans incoming and does not stop outgoing virus/trojans. If some how you get a virus/trojan pass the firewall it can transmit information outbound without detection.
I have used Zone Alarm (freeware) and it will catch everything coming in and going out.
As far as updates I install everything MS has to offer except the languague plugins.
Since you are using a notebook on the LAN I would also recommend a print server ($30 used, $70+ new) so when you log onto the LAN your printer is available. Most brands make routers with print servers built in, which start at $70.
All wireless routers have 4+ wired ports as well. You could setup a wired LAN except for you notebook, which would logon when it was in range. Wireless router refurbished router start at $40. Link to cheap routers.