|Did they tell you what your 'Security Mode', SSID, or Passphrase was? Normally a router will be setup with some form of security which you'll need to use your network. Windows7 does have a built in firewall, but you can easily update the settings to allow traffic over your network. (Click on the security center icon.)|
Check you little connection thingy in the system tray. You may need to find and connect to your network before anything else if the tech didn't set this up for you. If your network connection says it connected but limited, you should be able to log in the the router (http://192.168.1.1 normally) to see the security settings for your router. Hopefully he left you with the login/password, but if not, try admin/admin or admin/blank.
(Or this from another post on the DDr 2200...)
user name: admin