lets say you add a reg key that only works with sp2 in a sp1 system.

Would that reg key cause problems? If that system where to update to sp2 would that regkey still function?

Thank you for your time.

think windows would just ignore it, but what kinda key are you talking about as most will work on nearly all systems (other than the XP firewall ones)

registry keys are only places to store info that the os or apps need. if they need to know a value, they query it. if nothing queries it then its useless. if you change a value tho, then problems arise.

I can also confirm that this is true. I regularly deploy registry changes to Windows 2000 and 2003 servers via group policies. A lot of the time the changes only apply to Windows 2003 but still get deployed to the 2000 servers.

As long as the OS isn't looking for a value and the value you set conflicts with what it was expecting you should be right.

Okay thats what i thought, i was just makeing sure. From my knowalge of the windows registry it is a great place to dump structs for later use.

Yes, this happens to invovle the XP sp2 firewall, does that casue a problem? Like does sp2 whipe that directory of the registry when it is installed?

when sp2 gets installed your registry values will be overwritten with the default ones

Mostly that will be true. However, some programs store lists in the registry. And then query all values under that "folder" later. (Like the history of url's in IE). Possibly other programs and windows parts do the same.
By adding weird values to those "folders", you might be able to crash the program.

But that's just something from the top of my head.

Most of reg value will be over write, u can safe it by create backup in other directories and import that after window upgrade, scan the registry with reg scanner to remove conflick if any

As an aside paraphrasing a post on /.
(talking about WINE not being updated by WindowsUpdate)

Sound faesible?