Delay in startup

I had be grateful if you can help in diagnosing what & where the problem is. The mine problem is that when he starts his PC (switching power ON button from cabinet) it take 10-12 second to come up the single beep sound as well as first screen (BIOS info screen) to appear or display.

My PC configuration is P4 Core2Due E4500 2.2 Ghz, 512 MB (667) RAM, ASUS P5S-MxSe motherboard, 40 GB Seagate IDE HDD, 17" Samsung LCD Monitor (Windows Xp installed). Please advise /help me to overcome this problem.