Google and Microsoft are the best companies to compare Apple Inc. (NASDAQ:AAPL) to. Google carries a trailing P/E of 21 as its acquisition of Motorola Mobility Holdings has- at least temporarily- reduced its profits, though it has helped contribute to sales. Google's stock has also been down, following a peak in early October. It trades at 14 times forward earnings estimates, a fairly large premium to Apple. We can see Google having better growth prospects, but it's hard to say that it is undervalued compared to Apple at that price. Microsoft's forward P/E is 9, and that includes a likely temporary boost to earnings as new versions of Windows and Office are released. We think that looks a bit cheap in absolute terms, but it's tough to see Microsoft warranting an equal forward multiple to Apple.