I have this setup:

Gigabyte P35-DS3P motherboard
Asus NX1101 PCI network card
    (the one on the motherboard got fried a few years ago by a power surge)
Asus RT-N16 router
Windows 7 x64

I think the other specs are irrelevant here, but I'll post them if you say so.

Until a week ago everything was fine, but then my network became unusable: websites start loading but timeout before anything would come through (true for the web interface of the router as well), I can't reach the computer from my notebook and Windows' ping utility measures a ~50% packet loss between the computer and the router. Pinging localhost is good.

The router works completely fine when wired to my notebook. I also tested different ports on the router, different cables, different router and connecting directly to the modem, but it's still the same. Sometimes it works for a few minutes right after turning on the machine, but then it becomes crap again, but mostly it's useless from the start.

I've tried updating the firmware on the router, updating the driver for the network card (after which I started getting BSoDs in every 15 minutes), reinstalling Windows, swapping to Fedora 15 but none of them changed anything.

Does this mean that the network card is dying, or could it be something else? If it's the card, what model do you recommend as a replacement? (Could be PCI or PCI-Ex x1)

Thanks for your help.