hi if i update my cpu then do a cleen reload will my vista work with my new cpu ?

Probably - but there's much more to it than that. First and foremost, you must make sure your motherboard supports that new CPU.

Then, see here for the minimum hardware requirements for Vista. Note these are minimum - meaning Vista will run, but it is not likely you will be happy with the performance.

Also note this earlier thread:

http://www.d-a-l.com/help/showthread.php?t=47422

Unless some revision has passed me by it is my understanding that Vista's EULA will allow only one change of this nature.

This copy of Vista will be "frozen" on that machine in its current state.

No transfer nor additional major hardware upgrades.

I guess we need to make sure tango1 understands that the CPU is the central processing unit inside the computer and not the computer itself. As long as you keep the same motherboard and hard drive, I don't see swapping out the processor triggering any re-authentication process as that is not moving Vista to a new computer. Even reinstalling Vista on the same computer with a different CPU should not cause problems.

If by CPU he meant the "box" - that is, everything but the monitor, keyboard and mouse, then besides being wrong terminology, then that is moving to a new computer and that will cause issues with the EULA - as it should.