Anyone Using Netlimiter?

I have Netlimiter but the help file is practically non-existent and I know next to nothing about bandwidth so I'm fumbling my way around. What I would like to do is have Firefox and another app "X" both running, w/X getting the max amount of bandwidth possible when FF is idle. Then when I click on a link in FF I would like Netlimiter to give all the bandwidth to FF, temporarily cutting back on X's bandwidth allocation. Then after the page loads in FF, it gives the bandwidth back to X. And so on...

I assume I want to use either Limits or Grants or both? The instructions say one should first set bw speeds in Network Manager in order to use Grants, so I have set my Internet Zone to my max DL and UL speeds (1500kb & 256kb, respectively).

Now I'm not sure what to do next. I know I need to set Limits and/or Grants in the main window, but I'm not sure what to set them at in order to do what I want. I Granted FF the max dl/ul bandwidth, but that hasn't improved the speed w/X running, so I suppose there's something else I need to set somewhere?

Any help much appreciated.

Harold