1)He was using xp as OS for the PC(here in mumbai every home PC is mostly Windows esp xp.The rest r vista & win7 and in industries linux and mac is used).
2)Okk as far as auto run feature is concered,i can enable or disable it as per my needs in xp @least i dunno about vista or win7,if its possible thn i can do the same in those OS also.
3)I change the settings of autorun/autoplay by Win Services,i didnt knew it can be changed by registry.I would lyk2know 4m u,how 1 can change the same 4m registry.
4)Im just going through USB hack sections(which i earlier didnt saw)thnks for your suggestion.
5)Hmm...i dnt knw about U3 parition i hav2look into it.
6)There r some post related2USB,U3 partitioned,etc.If needed i will msg u.