Getting power management to work in Ubuntu

After noticing that my Laptop was not Spinning down its HDD, I decided to investigate, a quick google and on the first page I found a useful page: Power Management - Ubuntu Wiki . After going through the guide, I noticed that my Harddrive was spinning down very quickly. After a bit of experimentation with different settings for the spindown time, I realise that the issue was with the APM settings overriding the spindown setting. The solution was use a setting of 128 to 255 and the HDD will spin down according to the spindown setting - anything less than 127 (lower values = more power saving) and the spindown setting is ignored. I assume this is something specific to my HDD. Another change is that I have enable control of CPU throttling,

The result of these changes is that I am getting 15 to 30 more minutes usage time on battery (was approx 2 hours before).