First of all you can't make your downloads go any faster, you'll just have to download things with many sources, or wait longer. You say you are downloading from cable user and T1, well there are some people who claim to be T1, but really aren't.

Also let's say that a cable user has a 1000/512 connection. 512:8=64kbytes/sec. If that user has 8 people uploading from him, it's 64:8=8kbytes/sec. And then, if that user limits his bandwidth on LW to 50%, you can get a download speed of 4kbytes/sec.

That's just how it is, you can't change that unless you are really lucky and find a true T3 user with no one else uploading from him/her that has exactly the file that you want. It happened to me once, I downloaded a 1.3 GB file in two hours from one user.