The article was good.

Of all the ways,

SELECT SERVERPROPERTY('ProductLevel')

would be of much use as it tells what SP you are running, which most people want rather than version number.

And there is one more way to find this along with version number is Enterprise Manager.

If you right click on the Server (in EM), on the General tab you would see 'product version', which would tell you which service pack and version number you are running.