Downloading reduces performance

Downloading anything will make Windows 7 really slow and makes the audio distorted. This happens on my computer and my sisters laptop. I'm using x64 and she's using x86. This happens to her laptop when she's connected under my network. A clean install didn't fix the problem.

My router's model is WRT54G v. 6 and I'm using the latest firmware. My ISP is comcast.

ipconfig /release ipconfig /renew ipconfig /flushdns

did not fix the problem. This seems to be a Windows 7 issue as Windows XP seems to be unaffected.

Update: Yep, Windows XP definitely works fine. Downloading multiple files and no problems.

I don't think it's W7. I have the same router and me download is what it is.

Then maybe it's my modem? Anything I can do to test and diagnose the problem?

I'm not sure about the audio sound getting distorted when you're downloading. I didnt know downloading, makes sound?? As for the slowness of the downloads, are connected wirelessly or wired? Try both and see if it's the same?

It happens both on wired and wireless. When I download my computer gets really slow and my audio gets really choppy and I can hear "static".

Good idea, haven't really thought of that before. I've been using firefox on both the computer and laptop.

Same problem under chrome

The audio, is it only during downloading...like could you hear it during reboot/startup? Check for drivers updates, i doubt if it's loose cable/wireing?

I have the latest drivers and it doesn't have to be downloading for the audio to be distorted, it happens when CPU usage is at like 50% or more. Something was eating up my CPU usage but everything seemed to be normal. Like I said earlier, a clean install didn't fix the problem and that was a full format too.