|When you plug straight into the Ethernet, is this the Ethernet port of the wireless router or the cable modem?|
If it works when plugged directly into the cable modem, then it sounds like your wireless router is on the wrong ip subnet.
So we can check the IP setup please open cmd prompt and type "ipconfig/all"
You will need to to this twice - once when connected to the wireless router and once again when plugged directly into the cable modem with the ethernet cable.
Intel Core 2 Duo E6420
2x1Gb Corsair XMS2 DDR2-800Mhz
500GB Cavier Blue
500W FSP Bluestorm PSU