Main computer can't use Internet, laptop can only use Skype

My Internet connection has been very shaky these past few day and now it refuses to work on either of my computers except for Skype on the wireless connection of my laptop.

The main desktop is connected to the router and modem yet can't access the Internet, with a "no Internet access" sign, while the laptop says it IS connected yet I can only use Skype.

Can anyone provide me with help please?

Do the same as I suggested here please. http://www.sevenforums.com/network-...-have-valid-ip-configuration.html#post2038997

I've done the unplugging and waiting 30 minutes thing several times and now neither computers work. ):

What about the rest of what I asked for, the output of ipconfig /all?