Sb 1.6.2

I notice my WinXP; Vista and Win7 all have SB 1.6.2.
Is that the current version for all Windows? If not, shouldn't I have been notified that there was a newer version?
If I do have to update, will new version overwrite old version, or do I have to delete old version first?
Please advise.

No,the current latest version for the Windows operating systems you mentioned is Spybot 2.2.
http://www.safer-networking.org/about/compatibility/

Some people wish to keep Spybot 1.6.2,so my guess is that might be why the newer version isn't offered.

You don't have to get the new version,Spybot 1.6.2 is still available.
But,if you prefer to download and install Spybot 2.2,when it's being installed,it should offer to remove Spybot 1.6.2 for you,or you can always remove those versions first,if you'd like to do that,instead. :)