How to close application on Windows?

Hi,
I need to open some application from ruby on WinXP, get some action
connected to that app. and close it.

thread= Thread.new(0) {
system("abt.exe") # opening my app.
}
sleep(20) # time for start abt.exe
#getting data from abt.exe
system("hptcmd export")
#closing abt.exe - it doesn't work!!!!
Thread.kill(thread)
#abt.exe still active

Maybe I should kill a procces connected to that application so the
application would be closed ....?

Thanks for every advice
Mariusz