The newest upgrade to OS X, Snow Leopard, is now available for pre-order on Amazon, and currently occupies the top spot on the Software Bestseller List. There are several versions available, including a $30 upgrade version for those users who already have the Leopard version. Features of the upgraded OS include upgrades to popular features such as Exposé and Time Machine. In addition to the new features, Snow Leopard will free hard drive space when installed. The Windows 7 pre-sales are notably further down the list. Clearly this is an indication that Mac users are more excited and willing to upgrade to the new OS, and likely has nothing to do with the Windows 7 pre-orders being released further back in time. I'm sure the Windows 7 pre-orders didn't top the list when it became available, even accompanied by the tremendous sale prices.