Apu, thanks but I already knew that. He didn't tell me his res, so maybe his monitor limited him to 50hz. Some of the lower end / smaller monitors have very low refresh rates, especially at any resolutions above 1024x768.
My monitor is a 21" KDS CRT. It can do 120hz at 1152x864 (which is perfect for me for gaming... I don't like higher). My brother's monitor is a 19" flat Viewsonic CRT. His only does 85hz at 1152x864. You can notice the refreshrate drop even at 2". Imagine a 15-17" monitor at that resolution at 1280x1024 or higher...
I was just checking... but yes, you're right. With Vsync on, the refreshrate is the limiting factor. That's why I always override Window's refreshrates to what my monitor can do... either with Refresh Lock, or the nV CP. ATI has a proggy that Auto Populates as well.