thanks AgentGOD! for now i'll stick with xp 32 bit even if it won't be as accurate as 64 bit os, don't plan to switch to vista 64 bit: costs too much in term of money and performance loss in gaming. maybe when dx10 will really make difference i'll give it a chance.
i'll still keep using this utility as it is really time saving, will try using longer test with 15 or 20 passes, but not today: i've got 32.3°C in room!

btw, i've found that the issues with lcd poster, everest nb &sb temps, usb wireless dongle going crazy and so on was caused by my logitech g15 and it displays of everest readings: dectivating everest or the lcd plugin i have no more issue! i'm curious if someone else with g15 and using everst for temps readings can confirm this.