There is a new version of CPU-Idle out: and it's CpuIdle 6 and CpuIdle Pro 6 Alpha test version.

New features in v6 test version:

-added support for VIA KT333 chipset
-added support for SiS 735/745 chipset
-added Windows XP Style support
-when CpuIdle is started twice no error message will be.
-displayed, but the first instance will be brought up (ie. for use with the "Hide" feature)
-added support for latest MBM 5.1 Download CpuIdle 6 and CpuIdle Pro 6 Alpha Test Version