after configuring my router with my new ISP, whenever i hooked up the PS3, it would be given an in-use IP address from the DHCP server in the router and take down the entire internet connection.
after a big of googling, i found two suggestions for running PS3's with this particular linksys router (the WRT54G):
1. disable PS3's media server, or
2. disable UPnP is the router
i did both, and everything works fine now.