Whoohoo! Windows backup is there. Proeminently:

http://www.microsoft.com/windowsvista/features/default.aspx#wvC2

They also mention the Shadow Copy (aka Previous Versions). This is a standard feature now in Windows Server 2003, which is invaluable for many many customers. Now we are bring it to the masses directly into Vista.

Did you delete a file by mistake? Or did you overwrite it and lost your old work? Just right-click on it (or on the parent directory)  and you will see all its previous versions in the last month.