Is it possible to take a laptop that has both wired and wireless connections, and have it connect to a network (and the internet) wirelessly and then share the connection through a wire to a ps3?
Yes, use either ICS or something like analogx's proxy to share the internet. It depends on you ip address's. ICS is very odd in that it forces you to a particular ip. "Best Practices", Event viewer, host file, perfmon, antivirus, anti-spyware, Live CD's, backups, are in my top 10