Naomi,

IMHO depends on your target. Interprocess Communication can be messed up by MANY external factors, so if you write an app for a few thousand customers I'ld always go for the looping approach, as it can be easily enhanced/made more stable by adding other communicationg channels and is NOT resource consuming. Less chances of support having to sherlock hardware/OS/administration issues. WaitForSingle is more elegant style, but *can* be bad business.

YMMV

thomas