I am not sure that Belkin routers support this (well, not the ones I have seen).
What you are looking for is not standard QoS (Quality of Service), but traffic shaping.
I am not sure that there are any commercially priced routers that support out right traffic shaping, usually just QoS which is typically done on a service/port by service/port basis..... If however, you are the only one doing torrents or P2P (I am guessing!), you can prioritise this and it will mean that you will get most of the bandwidth.
Alternatively, again, if you are all using P2P of some sort, just make sure you are on a separate port to others and you should be able to prioritise yourself.... You want to look for something like this:
... And from this picture I just found, it looks like a Linksys router would be perfect for you - it looks like it also does traffic shaping, but called Port based QoS.. Not sure if I am right or they are...
Other than that, if you have a spare machine... but this is overkill, Ipcop can do traffic shaping.