Most of the gamers I knew stuck with XP during the Vista's time because it drained precious CPU cycles, but that's not the case here: Steam's released their latest stats on Windows usage, Windows 7 has already blown past Vista.
The stats break down this away: 42.78 percent on XP, 28.53 percent on Windows 7, and 27.91 percent on Vista. Consider that Vista's been out 3 years, and Windows 7's been out for 3 months. Also worth pointing out is that Windows 7 installs are 64-bit by a 2-to-1 margin, which as Ars notes, is now the most popular flavor of Windows on Steam short of XP 32-bit.
The gaming population on Steam isn't necessarily representative of Moms and Dads buying computers, but the fact that the deeply suspicious PC gaming community has picked up Windows 7 in droves does say something. [Steam via Ars, Neowin]