Windows Vista

In the earlier versions of windows operating system greater emphasis was on making a user friendly operating system and security concerns was neglected now with the advent of internet which has brought many threats also ,microsoft is focusing on security issue with much greater emphasis.
I heard that for security reasons they made fundamental changes in the architecture which will give Vista a big security edge over the earlier windows version.
But it is also a fact that in Vista beta version there are too many serious problems found for such a short period of testing .