if you had a trojan, might want to check the hosts file located in c:\windows\system32. i've seen some instances where a virus overwrites this file to force you to different sites or none at all.
since you cant even ping your other networked computers, the problem may be with the way you have the network setup. is it dhcp or static ip's? if you go to your network settings, and right click on the network connection, does it say enabled or disabled. if enabled can you right click the connection and repair it? if it fails on you, try removing the connection then removing the device. might just need the driver reloaded again, they sometimes go fooey on you.