Wireless internet not working consistently

Hello,
my internet was working perfectly fine until a few weeks back, it was hit by a virus (917ded.exe). I removed that by running the machine in safe mode, and installing superantispyware software, after which things looked fine. I also installed some Windows updates which were downloaded in my system. Now from last week onwards, internet works, but suddenly and randomly, even though internet icon shows connected, my bittorrent application shows high speed in Upload but either no/low speed in Download, the wireless connection status shows similar results (sent bytes change consistently but received bytes hardly increase but
I am unable to browse using IE or Firefox. After looking at several forums online, i have removed all antivirus, turned off all firewalls, but yet the problem persists. Soemtimes, disabling/enabling the wireless router restores internet, sometimes (mostly) the connection gets automatically restored after sometime. Another machine connecting to same wireless connection is connected consistently with no such problems.

I guess it has somehting to do with the virus/windows security updates, but i cannot figure out wht. Please help.

My laptop is a DEll Inspiron 6400, with Windows Vista home basic OS.

Thanks