Problem with laptop and router (Windows 7)

So I just got a new laptop with Windows 7. But it's having trouble connecting to the internet. The router I have is a Netgear dg834g. Two other Vista laptops are connecting to it without trouble. Anyway, what happens with the Windows 7 laptop is that it connects to the network and seems to be connected but websites don't load etc. (it's not a browser issue because other online stuff like Windows Live Messenger doesn't work either) So it says that it's connected to the router but there's no internet on the laptop. Occasionally, right after connecting, websites actually load (though slowly) but then the internet connection dies after about a minute. What's the problem and how do I fix it? I don't know much about the router's settings and stuff.

I tried changing the router's security settings to unsecured (to see if that was causing it). But this just messed things up even more; none of the laptops were able to connect to it like this and I had to use my desktop (which is connected to the router with a wired connection) to change the setting back.

Thanks for any help.

In reply to a post by phenomenal:

Occasionally, right after connecting, websites actually load (though slowly) but then the internet connection dies after about a minute.

That suggests the connection settings are correct, unless you are connecting to someone else's network.

Are you getting a good signal strength?

Does it work OK with a wired connection?

I got it to work. I just needed to change the connection's settings (change from WPA to WPA2) on the Windows 7 laptop.