How can I force an app to be completely hold in physical memory ?

I upgraded the physical memory of my notebook from 1 GB to 2 GB.
Now there should be enough memory to hold certain apps completely in physical memory.
Unfortunately I have to notice that 60% of the physical memory is still available.
Furthermore well known apps (like JBoss app server, graphic edit programs, programming IDEs,...)
are as slow as ever - always accompanied with lots of hard disc working (obvisously swapping in and out
space frames).

How can I force e.g. application mysample.exe (and its depending DLLs) in physical memory ?

Or - alternatively - how can I force WinXP to use memory as much as possible ?

J.