Overly Critical Guy writes "Microsoft's figure of 40 million Vista OEM licenses sold has less impact when weighed against the expanded size of the PC market, according to IDC numbers. The myriad of factors involved in determining success in the market makes Microsoft's constant comparisons to Windows XP less reliable as a growth indicator — particularly with Microsoft refusing to reveal the number of actual activated Vista licenses. 'HP reported year-over-year PC sales growth of about 24 percent, or about twice worldwide PC sales growth. Whatever HP is doing right, it's more than just Vista ... If Microsoft wasn't so hung up on XP comparisons as the benchmark, it could really demonstrate that Vista sales are increasing. The first 20 million figure really represented four months of sales, and that could have been positive data because Microsoft protected its customers' holiday investments. For free! Instead of making that point, Microsoft got carried away with making comparisons back to XP.'"