No, ISP don't use yet (well none that I know of). Windows assigns one just because it can. So does Linux now. Windows and Linux are notorious for dropping network connections when coming out of sleep mode. Hell, I just turn off sleep or hibernate mode and let the monitor go blank after 10 minutes.
In Windows 7 the icon in the systray can help you diagnose this. If there is a yellow triangle icon the network connection is not communicating with the modem, if it is a red X the card is communicating with the modem but seeing nothing from internet implying an outside failure of some type. For the latter you can try disconnecting the PC from the modem, turn off the modem and wait 20-30 seconds and repower the modem. Give the modem time to synch completely and reconnect the PC. If then the same failure occurs again, I'd contact Comcast.
How old is the PC and are you using on board NIC? I've have had on board NICs fail due to shoddy soldering. Might be cheaper to buy an add in NIC instead of a wireless dongle, plus the speed will be better.
That looks good, especially if router/modem is capable of N-band 5 Ghz.
Yes, the lights are there to tell you both the status and speed of the connection. Should be two lights, both should be green.
Honestly no. But stranger things have happened. When the Internet is working are both lights green on the back, and do they stay green while you are using the PC then? If so, I would still try resetting the modem as I mentioned earlier.
That sounds more like a modem problem than a NIC problem...do you know what the lights are on the back of the PC when you see the red X? If they are still green, it's definitely not the NIC.
