Why can't I connect to my wireless network?

[Garlock]

We just got a new modem today and we bought a wireless router as well. I've set up the network and everything looks like it should be working, except for one thing; when I go to the computer which is hooked up to the wireless network I set up, it attempts to connect and it gets stuck when it says it's acquiring an IP address. Also, I've noticed that the wireless network I set up sometimes doesn't show up on the list of networks. I've tried using the troubleshooting guide that came with the router, but its advice basically just consisted of 'Disconnect the modem and disconnect the router, then connect it again. What, that didn't work? Well then I don't know what the fuck your problem is. Why don't you call up some guy in India.'