thanks for reply but i was censored as both data were from virtual PC i.e. from Vista before slipstreaming 2.91 GHz and Vista SP1 after slipstreaming 32 MHz while i found one thread indicating slowdown of system by installing slipstreamed Vista SP 1 http://www.msfn.org/board/Running-Slower-a...er-t116986.html though i will install it on physical machine let you know the status