Use uTorrent as your client since it's one of the best ones out there.
Run the utorrent set up guide from the Options menu and run the test first. When it's done, look at Upload Limit and see if still says what you were getting before.
Go to Preferences --> Bandwidth. Either keep the max upload rate or set it to 0. Increase global max # of connections if you're seeding a lot of torrents but don't set it super high.
In Connection, make the UPnP, NAT, Windows Firewall boxes are checked. Uncheck randomize port and just pick an open port. Then go to your router and enable port-forwarding and type in the number you picked.
If you have an old computer with old harddrives, go to Advanced in preferences, then Disk Cache, then check the first box Override automatic cache size. Increase the number slightly and see if makes a difference.
You can do all of this and still not see a difference. I used to get a max of 320 kb/s for upload and 1.6 mb/s download. Then I changed routers and got a new one, and upload increased to 424 kb/s, and download to 2.1 mb/s.