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"