I can't access some sites

hi guys,

was hoping for some help...i've had internet explorer for a few years..not sure what version cause i dont remember updating it..but i just added a wireless adapter to my computer last night (previously i had dial up) and my internet works..but I can't get onto HOtmail, download a new or any version of msn messenger..get onto facebook...i end up typing in my name and password and it takes me to a page that says site cannot be found..i've followed all the suggested options to fix the problem but still I can't get into that site...sometimes I have problems getting into Yahoo mail too...any suggestions?

I had norton antivirus previously and it caused problems and woudnt fully uninstall itself..i know have McAfee..could that be a problem?

thanks for your help!!!