Hmm.. my ASUS laptop with 2 GB Ram once tried to hibernate in WIN XP (about 2 years ago)... but could not, due to too much RAM and continued 'running' full speed. It was beeping when I got home it was close to 100 degrees (Celcius, boiling water)
Quickly installed SuSE 10.1 (about 1.5 years ago) and it hibernates the way I want and has nice CPU frequency scaling options

And, btw, I had to send the ASUS back to ASUS (doh) thrice due to failure to the DVD drive (2×) and a monitor failure (widescreen went back to 4:3, strange...) and I was allowed to take out the Hard Drive for safety reasons... (all three times btw)

(bought mine at MyCom in the Netherlands, had to send it back to ASUS as they don't do warranty issues themselves, oh they could, but it would take longer, would it make sense to phone the PC manufacturer?)