The first letter of the program is the accelerator and there's nothing you can do about it. So if you have ten programs by Microsoft, they all use the accelerator "M". (Yes I hate this too. The first thing I do after installing a Microsoft program is go into the Start menu and delete the word "Microsoft" from the front.)
For Win32 menus, the ampersand character acts as the marker for the menu accelerator. For example, you would set your menu text to "Save &As" to set Alt+A as the accelerator for the menu item.
This isn't done for the Start menu and for the Favorites menu because the ampersand appears in program names occasionally. Otherwise, "AT&T Internet" would end up displaying as "ATT Internet". (This was a real problem in Windows 95, where the Start menu was constructed from your old Program Manager groups, and occasionally we'd run across one that had an ampersand in its name.)