Wireless card and Comcast

I am posting this from a friends computer that has a recently installed netgear pci wifi card. The card is functional but downloads are corrupted and it seems like ports arent being forwarded. The ISP is Comcast. What to do?

>>1
Have you tried using a wired network link on the same connection? If the wired computer is fine, the problem is the card and/or its drivers. If not, then the network connection is damaged, and you need to complain to Comcast.