iPhone 4 WiFi issues with Linksys WRT54G

I hardly ever use WiFi for my iPhone4 but when I am in my apartment, I would like to considering I get dull AT&T service (go figure). For some reason, my WiFi will not work. It says that I am connected on my iPhone and my laptop gets a signal, but on my iPhone the Safari page can never open and my apps that require internet do not work. I have tried it ALL. I have tried to use WiFi only on airplane mode, I have deleted and re-typed in my IP address, unplugged the router and waited 30 seconds, shut down everything, reset my network connections, everything on the forums I read, I tried and nothing works.

I believe this could be a problem with my Lynksys router because my mom tried to connect her Nook up to my internet and it didn't work either. I really don't want to buy a new router and don't think I should, isn't this the point of getting a wireless router? My computer works fine though, I can take my laptop anywhere in my apartment and get full bars for wireless. I know this is an Apple forum, but does anyone know what the problem is and how the heck I can fix it before going nuts? 🙂 And if it is my router, how can I get it to allow smaller devices on my wireless? I am by all means, very unintelligent when it comes to computers and wireless--so please, very detailed help would be so nice!