My laptops internet will not connect.?

I just recieved my new dell inspiron laptop wednesday. I configured the settings and everything that same day and used it thursday and friday and both days it worked great. Today however my internet connection is extemely slow and frequently goes out completely on my laptop. I called the internet company and they rebooted the modem twice. The wifi connection is working for my Ps3 just not my laptop. Can anyone give advice on what may be the problem and how to fix it?