First off, you need to know what your LAN (Local Area Network) setup is. Most LAN's are a 192.168.XXX.XXX with a Subnet Mask of 255.255.255.0. In order for your PS3 and other networked devices to talk to each other they must be in the same LAN. This means that each of their IP's need to have the first three groups of the IP, XXX.XXX.XXX.000 wher the X's are, to be exactley the same. Some wireless router's put the wired and wireless on two seperate LAN's.
To see how your network is setup, I recommend you use your working computer and go to a DOS prompt.
To do this, go to Start, then Run and type in cmd and press enter. You now should be at a DOS prompt. Type ipconfig /all and hit enter. What you want to know, I recommend writing it down, is the IP Address, Subenet Mask, Default Gateway, and DNS servers.
IP Address: This is the adress you gave (Static) or the router gave your PC (DHCP).
Subnet Mask: Basically a LAN within a LAN. You just want this to match between your PS3 and PC and Router and is usually 255.255.255.0
Default Gateway: This is the IP Address of your Router or Modem. You can usually type this address into your internet browser and log into it's GUI (Graphical User Interface). This is how you setup your router or modems options.
DNS Servers: These are the IP Address's of your ISP's Domain Name Servers and you usually have two of them and sometimes the first, primary DNS is your router. They resolve IP's from XXX.XXX.XXX.XXX to XXXXX.com. For example. www.google.com is 22.214.171.124.
Now what you want to do is get your PS3 to talk to the rest of your network. What you should do at this point is log onto your router by typing in your default gateway IP address into your internet browser. First check to see if DHCP is enabled. If it is not enable it and see if you can now connect. If it is and you can't connect and are wireless, check to see if your LAN settings and Wireless settings have the same network settings, that the first 3 group of numbers are the same, and the subnets are the same. I remember working with a Linksys that would have the wired side as 192.168.1.XXX and the wireless side set to 192.168.2.XXX. These networks won't talk to each other. If this won't work for you then put in your own settings on the PS3. Manual setup. Use the IP address's from what you got when you went to the DOS prompt. The only thing that will be different is the IP address. For example let's say your computers IP, the one you got when you typed ipconfig /all at the DOS prompt, is 192.168.0.2, you would want your ps3's IP to be 192.168.0.XXX, where XXX is a number between 2 and 254 and not what other devices on your network have. I would use a number between 10 and 20 if you don't know the other IP's of the other devices on your network.
If you have any further questions, ask. Hopefully this will help some of you....