no internet connectivity

I have a new Dell laptop with Win XP. I've always had an internet connection until this morning. My other two computers in the house can connect fine but the Dell cannot. I fear I have clicked something that prevents me now from accessing the internet on this Dell. Can someone get me started on a solution? One thing that is different is I've started filling out surveys online for cash reimbursements. Not sure that's affected my connectivity though.

What kind of Internet connection do you have? Eg: Dial-up, Wireless, Broadband (DSL)? What kind of connection does the other two computers use? What kind of surveys were they? Was it those "colorful" flashy kinds? Also, have you experienced any malware trouble (pop-ups, changed homepage)?