You can make Windows XP load frequently used programs from quickly accessible locations.

Windows XP is smart enough to analyze user behavior and (somewhat!) adjust accordingly.

An example of this behavior has always been the various MRU lists (Most Recently Used).

Periodically (I believe this is by default 3 days), XP would rearrange the location of some of the most actively used programs and locate them on that part of the disk that is quickly accessible.
(Believe me, all parts of disk are not equally quick accessible; some are quicker to access and some are not. A simple law of physics).

Anyway, if you want to initiate the 'housekeeping' activity at your will, go to START-RUN and enter:

Rundll32.exe advapi32.dll,ProcessIdleTasks
Note: The parameter "ProcessIdleTasks" needs to be entered case-sensitive.

This will then start the reordering process.