I have a problem with getting internet on the PS3. I'm quite the noob when it comes to internet connections, so please bare with me.

I have 2 PCs connected to the internet on one IP adress (you can lan on the 2 pc's). Now, I'd like to connect my PS3 to the same network. This network is called "Sitecom" (after my router, I presume).

After I configured everything, I can go online on my PS3. BUT, when I want to online with my PC again, I can't. So I reconnect my PC and BAM, the PS3 can't go online anymore.

This happens all the time: I can't go online with my PS3 and PC at the same time. I reckon this has to do with both operating on the same IP adress, which is not possible simultaniously.

Does anyone know how to fix this problem so I can go online on my PS3 and PC at the same time? Thanks.

Go through your routers settings and set a static IP address (which is different from the one the PC uses). And then, in the PS3 settings, change the IP address settings to the address you specified in the routers settings.

This may be a stupid question, but how do you get into the router settings?

usally a router can be accessed by typing in a numeric web address of 192.168.2.1 or something similar. It depends on what brand of router you're using.

Alright. When I do that, I need to specify a username and password, though I can't remember ever having to give up a username or password for my router...?

^^try looking at the documentation that came with the router. You could also try "admin" for the username and " " (~empty~) for the password as that is a common default for older routers; though most newer routers have a random alphanumeric password for the default (e.g."00s76a54fr675") So yeah, the defaults should be listed in the documentation.
Also, and I don't know if this could be the problem, but I had a similar problem with hooking more than two computers to a router at once and it turned out the router was messed up. If you can't get it it to work any other way, I would recommend purchasing a new router. A decent combo wireless/wired router (wired for your desktop(s) and wireless for your PS3/laptop) only costs like $70 or so.
Also, if anyone ever tells you that wireless is too slow for gaming, it's not true. Wireless G routers, which are the virtual industry standard, have a maximum data tranfer rate of 54mbits/s. The fastest internet connection I have ever even seen advertised is the Premium Verizon FIOS package @ 30mbits/s, which is only 56% of Wireless G's max rate. (and that package costs $140/month!!)

Try using stupid things like admin, password, administrator, your router name, etc.

Usually, if it's left on default it would be:

Username: Admin
Password: Password

-or-

UN: admin
PW: admin

If not, it'll be in the documentation of the router.

Quick fix suggestion:

I am aware that this isn't the best solution, but it works anyway. Plug the network cable into the back of a running pc and go online trhough that. If you have issues getting that to run, then go to your configscreen, select network connections and slect both lan connections in there, right click and select network bridge.

This solution will never receive any awards, but it does the trick. I still suggest looking into your router anyway.

Are you sure you have a router? Some ISPs offer multiple IP addresses to a modem and they won't let you obtain more than those addresses. If you called up the cable(?) company and told them you need to connect two PCs then they might have set you up this way. You can usually check your bill to see if you have extra fees for additional IPs. You don't need a router and both PCs are internet facing. (ie: they don't have private addresses.) A way to check this is to go to a command prompt in Windows (I assume that's what you have) and type: ipconfig

It will give you IP addresses (DON'T copy them here in case they are public IPs or you might have someone playing with your PCs) but if they start with 192.168, 172.0, or sometimes 10.0 then they are private and you are likely behind a router. Otherwise, you are setup with multiple IP addresses. (and likely paying too much for your internet.)

If your behind a router, there are specific settings per device... we'd need more info.

Yes, I have a router. But let me get this straight: each router has its own IP? Do when I buy a second router and plug it into the PS3, that will work too?