Sure - you can delete it with disk cleanup.

Make sure all your programs are working first - if the installer found incompatible ones they would be left in Windows.old rather than copied to the new...

Leave it a few hours and it should calm down.. TH2 is an upgrade to the OS not just a patch (that is why you get the Wondows.old etc) so it is doing all the same things as it did after you upgraded...