The idea was in the right neighborhood, but the recommendation was not a safe option with ACPI power management already enabled for the system during the installation of the operating system. Simply changing the drivers for the HAL type in the Device Manager could make the computer highly unstable, or render it unbootable.
In order to have that "It's now safe ... " screen, you'll need to reinstall or <A HREF="http://www.microsoft.com/windows2000/techinfo/reskit/sa..." target="_new">repair</A> Windows 2000, with ACPI features disabled in the BIOS, and APM power management enabled. With Win2K and WinXP, you'll also need to manually select the Hardware Abstraction Layer Type during Setup.
Note: WinXP Home Edition does not support APM, only ACPI.
I would further suggest that you back up your personal files before making these changes, as specifying a different HAL will alter the way Windows assigns IRQs to the devices in the system, and some of your programs may need to be reinstalled afterwards.
Here are some addition links to information that you may find helpful:
In any case, it will be necessary with all operating systems to update the chipset drivers, and in the case of Win2K and Win98, reinstall the latest version of DirectX. Win2K will also need Service Pack 2 reinstalled before updating the chipset drivers. Other devices may also need fresh driver installations, such as the video card, sound card, and NIC card. In many ways, this is a fresh installation of the operating system, and should be treated as such.