Oh come on, not another "let's bash MS cuz Bill Gates is evil"...
Windows 7 has '7' as its version number, because it is in the NT 'branch' of Windows, as opposed to Windows 95, 98 or ME.
With Windows Vista having the official version number 6, there's no big deal in Windows 7 having '7' as it's version number. The only more or less weird thing with the NT version numbers was that the first real version of Windows NT was 3.1 (thus officialy named Windows NT 3.1). This was done for marketing purposes, as at the same time Windows 3.1 (which was developed into Windows 95, 98, ME) was already available.
Be happy they started using version numbers again, as opposed to names like 'XP' or 'Vista'.
This is (and should be!) common knowledge. Check
this for reference.
