WinExec(), process handle?

[Cassius]

Hi!
I execute application by using WinExec() function. I want to know if
the application is finished or not. How can I check it?

The application is 7zip, I match Sleep() function for enought delay -
after unpack of files my application deletes packed file. I'm affraid
that other equipment (other PC with different hardware configuration)
will make the operation of unpacking files with longer time and the
packed file will be deleted too fast :( Do You know any way to check
the status of active process which is executed by using WinExec()
function ?

I tried to use CreateProcess() but it doesn't want to work with
7zip.exe :(
I'll be very grateful for help :)