yest night my friend updated his windows vista home premium(preloaded), and after updating, he restarted his laptop
after restart, windows installing the update components, the install takes very long time, so he left it overnight

but when morning he woke up, the install is not complete yet, as that time he's rushing out, so he just force off it, and bring the laptop out
now it seems that the windows is sort of corrupted, a lot functions seems not working and it hang easily

so anyway can revert the update? tried system restore but it seems doesn't work, restore to factory settings will be the last resort if no solution

I'm assuming restore factory settings in reformat? Try to go to Windows Update in IE 7/IE 8 BETA and do a manual update through the browser.