That doesn't sound like a network card problem, it sounds like a AV, firewall, or AS prog problem
Anti Virus is Avast. AS? little confused
Spybot search and distroy
You really should have 4 things protecting your computer, often they can come in suites, anti-virus, anti-spyware, anti-adware, and a firewall.
Anyways I dont get your problem, you get slow internet when downloading things, but gameing and browsing are all downloading to, Gaming will use 30kb/s up and 30kb/s down constantly, or enough to max out a 56k modem. Surfing, with websites the way they are now, up to 1Mb a damn page, sometimes more, youtube, depending on what your watching anywhere from 300kb/s to 6Mb/s. So I cant see how this is just a problem when "downloading"
im using Vuze as my torrent downloader. For whatever reason i can game and surf all i want, but the moment i go to download something with it, inside 5-10 mins if im lucky my network card goes kaput. After that, no gaming, no surfing, no nothing till i restart my computer. I dont know, maybe my computer doesnt like vuze. But i have had issues with larg downloads from websites (in the gig region). Thank god that website saved where you were in the download cause i had to restart 4 times to finish.
I will try that.