I may be sounding like a total idiot, stating something everyone might already know. But I know that in all my time being obsessed with computers, I had no idea how much Windows tweaks could actually increase network speed, particularly uploading speeds.
I used to upload at around 50kb/s MAX in utorrent, but after the tweaking I can get up to 200 kb/s uploading EASY.
TCP Optimizer is what I used:
SpeedGuide.net :: TCP Optimizer / Downloads
Here's a screen shot of my bandwidth testing:
http://i149.photobucket.com/albums/s.../speedtest.gif
I'm just really amazed right now. I can't believe I wasn't aware of this until now.