There are a couple of alternatives to address your problem, the simplest of all being the use of a UI timer control; it is to be said, though, that achieving and maintaining such a resolution on Windows systems is not so easy, as there can be several running OS tasks that can interfere with timer pacing.
One possible alternative is the use of Asynchronous timers, a special instrument that creates a timer based on multimedia timers and running in its own thread; the instrument can be located in \toolslib\toolbox folder. Programming with asynchronous timers is made easier by the fact that they accept the callback of UI timers, so once you have created and tested your code using a UI timer you can then easily switch to an async timer simply discarding the timer control and creating the new timer with that callback. Async timers are quite more regular than UI timers, even though they can still be affected someway by OS activity.
The last, more complex alternative before using a real time OS is a regular multithreading application. There are several documents on multithreading that you can find on your disk or on this site so if you want to go that way I suggest to start reading Creating Multithreaded Applications chapter in the Programmer's Reference in the help.
