Often companies will claim a "sellout" in order to hype incredible demand for its product. However, these claims are pointless without any firm numbers -- after all, there's a big difference between moving 100 and 100,000 units. Now we're getting word from Japan that the heavily discounted Windows 7 upgrades that went up for pre-order on Friday are sold-out. While no numbers are given, the 17 retailers involved in the pre-order sales who presumably have no vested interest in trying to inflate perceptions on behalf of Microsoft, report sales as "considerable" and taking only 1.5 days (of the 10 days planned) to burn though the alloted inventory. A quick check on Amazon US and Canada shows the same pre-order prices we saw Friday. Still, it might be wise to take notice of the "while supplies last" disclaimer if you haven't already.