Not BIOS but Control Panel under Power Options. Go to change advanced power settings and there are quite a lot of settings to tweak. Btw in BIOS there is an option for System FAN always ON. I disabled it but enabling it wont make any difference cos I dont think temp will go as low as 30 or 20C.
Did you format or make partition before installing? I can install Vista Ultimate in less than 45 mins.
I think that should be ok. 65C maybe your are using Java or playing Youtube. Normally I would get around 55-60C when surfing. If totally idle around 45C. Load up to 80C. 90C is a bit high and dangerous. Make sure nothing is blocking the air vent behind the notebook. You can elevate the back are of the notebook too so that the air vent can move out the hot air faster.
Actually AMD is hot but the poor ventilation design for this model makes it worst. The discrete HD 3450 may be the culprit. Make sure you install the video card's driver and software correctly and enable Powerplay. It's a budget notebook so cant expect much from HP.

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Added on October 7, 2008, 9:52 am

Sorry cant help u with that cos I dun use headphones. Anyone else can help? Or you can try to call HP or use Live Chat although their technicians cant help much

Btw, how many devices you can find under Playback Device in Control Panel.