ASYNCHRONOUS CALLS how do we FIGURE OUT this

Hi All
We are using 8800 GTX, Some says, It doesnot support Asynchrnous Calls, But when we experiment it shows it supports and when we run asyncAPI given in SDK under projects, It runs

Can Anybody of you please clearify
1)How To use this Asynchromous Calls with Events, We got wrong results on this
2)How to Calculate GPU time and CPU time,
Thanks for your reply
Dev