I have a pc and a laptop and my ps3 connected all the same time i'm on 20meg bb but your connection will deffo be fine for online gaming with the ps3 or downloading from the PS3 Store without any huge lag
You'll need a router as Darth and Webcrawler said and its best to connect all wired rather than wireless (using an ethernet cable) i'm currently using a Belkin router for mine but there's plenty you can buy just make sure you get one with enough ports for your needs (4 port!)
You can also share your music, pictures and video from your other computers to your ps3 which is cool, info how here
if you'd like to
It's all very easy to setup whether your an amateur or not
if you have any trouble with anything feel free to post again whats up or send me a PM and i'll be happy to help you get sorted
Have fun with your ps3! it's a great time to get one with all of the best games now on the horizon GTA4 for example!!
~ Kitty x