Buy what your torrenting
very often (at least in my case) you can't buy what your torrenting. Things like AMVs (AMV hell in particular), community movies like Star Wreck and Big Buck Bunny (I know you CAN buy these, but they are officially distributed for free by the creators via torrent), foreign or very old movies/games (that I wish I could buy, but can't), and dare I say it, porn (why would you WANT to buy some of that stuff? some high quality movies should, but the "wierd stuff" can't be purchased anywhere that I know). the point is, a lot of people torrent legitimate things, so its a valid question. And I can't think of anything I torrent that I could run out and "Buy" to recieve the same experiance. Otherwise I would.
(this might be a special *me* thing, because my friends make fun of me for it) or you're torrenting it because you're too lazy to find the disc you have purchased (its a bad habbit of mine, but its so much easier to watch a digital copy than to find and put in the DVD. Especially is the case with some movies I own on VHS and I don't feel like getting the DVD copy right now because it doesn't have enough special features to make it worth it or something similar)
To the OP. It really depends on what your getting. try downloading one of the AMV Hells. (usulaly about 2000 seeders at any given time) and if you're not pulling off more than a few 100 kbps at least, then your ISP must be filtering torrent packets (which an ISP could do if they wanted) or your internet is not as fast as you want it to be.
Having a good router than can handle a ton of connections helps too. Make sure your required port(s) is/are open. And don't let your upload limit be above what your service can handle (you didn't say how fast your connection was, but when the torrents are off, run a speed test and make sure your torrents are never above your upload. Also bear in mind that most speed tests are in 'bit' where torrents are measured in 'bytes' which would be 8 times the bit number).
There are many other things you could check too, most of which I don't feel like going into. Personally I like to keep the number of connections at the same time to a minimum and try to force higher MTU, but others would recommend against that.