Can anyone tell me why this is happening?

Something that has been bothering me for some time is that my downloads always seem to be capped at 750 KB/s it doesn't matter where I download from sometimes it will start out faster but gradually find its way down to 750. While if my wife downloads on her laptop through our wireless she goes 1.4 MB/s at times. This is almost double the speed and shes not even wired in.. Whats even worse is when she decides to download something when I am as well she will take all the bandwidth and I might as well just pause mine till shes done.

Speakeasy says I have a download rate of 17196 kbps which is 2149.5 KB/s This is slightly more than 2MB/s So why the heck is it that any downloads I have get capped at 750 KB/s? While I certainly don't expect everything to download at 2MB/s it should certainly shouldn't be giving me the same 750 KB/s. Does anyone have a logical answer to why this is happening and perhaps a solution?