Below are a few screenshots of Millennium. These should give you an idea of what the program looks and feels like, and the type of functionality that you can expect to find.
This is the main Millennium window, the 'memory view'. It shows you exactly what is in your sampler. You can delete, duplicate, rename and edit all your programs, samples, etc. all from this window.
This is the same 'memory view', in detailed mode. Here you can sort your programs by program number and see the size of all your samples in one window.
This is the keygroup editor. It shows you all the different samples assigned to each keygroup, and lets you change the assignment by dragging it with the mouse.
Double clicking a keygroup brings up the keygroup editor (right). This window contains all the settings that are unique for each keygroup. All the controls are clearly grouped, and the envelopes can be modified by dragging the points of a graph.
Above is the 'adjust BPM' dialog box. Enter in a source and target BPM and it will adjust the pitch of the sample accordingly. No more calculators needed. It can even try and auto-detect the original BPM, using a process similar to the BPM counters used in DJ mixers.