Restart the computer.
At the initial Sony screen, press the F2 key to enter BIOS setup.
In the BIOS Setup window, press the RIGHT ARROW key until Advanced is selected.
In the Advanced menu, press the DOWN ARROW until Speaker Volume: is selected.
Press the ENTER key.
In the Options window, press the DOWN ARROW or UP ARROW to select 0.
Press the ENTER key.
Press the RIGHT ARROW key until Exit is selected.
Press the ENTER key.
In the Setup Confirmation dialog box, press the ENTER key.
If the sound is not disabled, continue this procedure.
Restart the computer.
At the initial Sony screen, press the F2 key to enter BIOS setup.
In the BIOS Setup window, press the RIGHT ARROW key until Advanced is selected.
In the Advanced menu, press the DOWN ARROW until Show VAIO Animation Logo is selected.
Press the ENTER key.
In the dialog box, press the DOWN ARROW to select No.
Press the ENTER key.
Press the RIGHT ARROW key until Exit is selected.
Press the ENTER key.
In the Setup Confirmation dialog box, press the ENTER key.

Hope that helps you and others turn off that pesky Sony Vaio chime!

The following are steps to mute the Windows sound as well

Windows XP
To turn off the startup sound in Windows XP, follow these steps:1. Click Start, click Run, type mmsys.cpl, and then click OK.
2. Click the Sounds tab.
3. Under Program events, click Start Windows.
4. In the Sounds box, click (None), and then click OK.

Windows Vista
To turn off the startup sound in Windows Vista, follow these steps: 1. Click Start , type mmsys.cpl in the Start Search box, and then click mmsys.cpl in the Programs list.

If you are prompted for an administrator password or confirmation, type your password or click Continue.
2. Click the Sounds tab.
3. Click to clear the Play Windows Startup Sound check box, and then click OK

I hope this is helpful to you… Good Luck