Windows Operating System traffic on our sites

As we approach the 2nd anniversary of the release of Windows Vista, I couldn't help but notice that the traffic on our sites still show a huge margin of Windows XP users. Here is the raw data on two of our sites.

NetScanTools.com (10,700 hits)
On this site 93.4% of our hits are Windows users, 3.8% are Linux users and 2.3% are Mac users. Here is a breakdown of the Windows traffic:
77.8% Windows XP
17.2% Windows Vista
2.8% Windows Server 2003
2.2% Windows 2000
0.1% Windows 98
0.02% Window ME
and 1 person using NT4 (must be Boris)

nwpsw.com (600 hits)
On this site 92% of our hits are Windows users, 6.5% are Linux users and 1.2% are Mac users. Here is a breakdown of the Windows traffic:
81.1% Windows XP
14.6% Windows Vista
2.5% Windows Server 2003
1.8% Windows 2000

This data shows that people are not only still using XP, they are favoring XP. To be fair, there has been a couple of percentage points increase in Vista traffic since the first of 2008. I wonder what the market penetration was for XP at the two year mark? I just thought this was interesting.