Вот пример от Апплемана
Sleep, SleepEx

VB Declaration

Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Long)
Declare Function SleepEx& Lib "kernel32" (ByVal dwMilliseconds As Long, ByVal _
bAlertable As Long)

Description

Suspends operation of a thread for the specified time.

Use with VB

No problem.

Parameter Type/Description
dwMilliseconds Long—The time to suspend the thread in milliseconds. The constant INFINITE to put a thread permanently to sleep.
bAlertable Long—SleepEx only. Set to True if an asynchronous I/O transfer has been initiated with a ReadFileEx or WriteFileEx function call, and you want the function to return so that the I/O completion routine specified by those functions may execute.
Return Value

Long—SleepEx only. Zero if the timeout elapses, WAIT_IO_COMPLETION if the function returned because of the completion of an asynchronous I/O operation.

Platform

Windows 95, Windows NT

дык в интернете как грязи - vbrussian.com, vbnet.com, а у апплемана просто все в одном флаконе. Если хочешь могу слить архив Vbpg32.hlp - 30 метров.