No it not the router. There are a lot of things that contribute to the speeds that you get. Let the experts elaborate on the same, but from what I know (maybe i am wrong), they are as follows (in no particular sequence)
1. Your phone line's stability - the line does contribute a lot to the speeds.
2. The softwares that you use - Check your torrent speed and regular download speed (rapidshare)
3. If there is a problem with torrent speed, you can do a lot of things (search TE) to improve the speeds (open half connections, set the upload speed, check private torrents, etc.)
4. Try checking your speeds @ speedtest.net at different hours.
...and most importantly ..
5. What plan are you using? If you are using a 256 kbps plan, you will not get more (but then you would not get 256 too, it would hover around 200 or less). If you are in a plan that supports 2 mbps, and you are still getting 256 kbps, you may have to contact your exchange to rectify that.
