Add Windows 8.1 version in CheckOS().

git-svn-id: https://peerblock.googlecode.com/svn/trunk@670 d3e0e2f6-51e0-11de-b413-c5e99dc0a8e2
Remove Windows 2000 support.

git-svn-id: https://peerblock.googlecode.com/svn/trunk@671 d3e0e2f6-51e0-11de-b413-c5e99dc0a8e2
res/about.txt: Remove stray double space.

git-svn-id: https://peerblock.googlecode.com/svn/trunk@672 d3e0e2f6-51e0-11de-b413-c5e99dc0a8e2