computer closest to modem and router, slower than others...

My computer is right next to the modem and router...yet the internet is slower than my two other computers, which are about 50 feet away. Something is wrong here. Can someone help me?

Have you done spyware/adware/virus scans on the computer to make sure that there isn't an issue in that regard?
Is there a software firewall on that computer?
Are all of the computers wireless, or are some wired, or all wired?
If the slow PC is wired, have you tried a different cable to make sure that is isn't an issue with the cable?

Yes they're all wired. I'm not sure about the firewall, but I see that the Windows Firewall is on. I do ad-aware scans every other day. And I did try a different cable. I also just ordered cat 6 cables, because all the ethernet cables I'm using is cat 5.

Can you describe further how you determined that this machine is 'slower' than the other ones in the network?

Game ping times better? (same game same server?)
Faster download rates? (is it downloading same file from same server?)
Internet pages load slower? (using same browser with cache cleared looking at same page?)

Need some more info to go on from here...

Games are the same for every computer. Download rates are a bit faster on the other computers, compared to mine. The one that I really want to fix is the web pages. It loads much slower on particular websites for some reason. For example, the TF website, loads fine on mine, and so with the others. They all loaded that pretty fast. But especially for youtube.com....It takes mine, about 2-10 minutes to load everything, while the other two, loads it in 5-10 seconds.

That sounds like it could be a software issue. I Would check to see if you are using the same verisons of software, both the web browser, and windows media player. Also, try testing again after that with the windows firewall off.

As far as 'a bit faster' with downloads, how much difference exactly?

They're all using the same versions of firefox and windows media player.

Forget the downloads. I think it's because I had torrents on. But even with torrents on, my other computer downloads fast. For example, I downloaded a driver from nvidia to test. The computer that is about 25 feet away downloaded the driver at an avg 600kb/s. The computer from 50 feet away, downloaded it in 150kb/s. While mine, which is next to the router and modem, downloads the driver at 200+kb/s.

I tested with the firewall off, still the same.

Hrm, that is certainly interesting. Where all of these downloads done at the same exact time, or one at a time in the same couple of minutes. The amount of traffic at that server is also a factor, and it could be that there are a number of servers with that file, and it dynamically sends the file to you from a server with low activity.....

Its a shot in the dark, but try doing the SAME test again on all 3, but UNPLUG the unused PC's from the router, just to eliminate any traffic they might be putting ont he network, to see if it makes a difference.