I haven't fully understand but i try to sort it out for you:
So either your modem is only modem or it's a modem-router (here you have wireless or wired-only).
And you need wireless for ps3 and laptop?
So:
modem-only: you buy a wireless router(caution if your modem is a company modem, can be tricky) and access points (little usb cards) for the laptop (if it doesn't has wireless integrated). In this case, buying a whole new modem-router is a good alternative becasue the setup will be a ease.
if you already have a router ready modem: you good to go , maybe except the access points.
wired connection = less setup
wireless = Setup but NOT complicated.
And take Wap2 as wap can already be easily cracked.
If you need to buy all new, look for n-draft router and a.p., as it is the fastest, commercial available wireless connection for the moment
I have dlink router (120€ high range) and asus access point usb (20€
