Yep.
But you won't be able to have the PS3 & your PC connected to the modem at the same time. And you'll need to turn the modem off & on again each time you swap over.
http://homepage.ntlworld.com/robin.d...swap.html#swap
A better, long term, solution would be to get a router. They're quite cheap, even wireless ones. Then you could have the PS3 & PC connected at the same time.
Linksys are a popular choice here... BEFSR41 wired, or WRT54G wireless.