To upgrade on day one: Lion

To upgrade on day one:

1. 

   Step 1: Make sure your Mac can run Lion.

   Your Mac must have an Intel Core 2 Duo, Core i3, Core i5, Core i7, or Xeon processor to run Lion. Find out if your current Mac has one of these processors by clicking the Apple icon at the top left of your screen, then choosing About This Mac.
   
2. 

   Step 2: Make sure you have the latest version of Snow Leopard.

   Get up to date with the latest version of OS X Snow Leopard to purchase OS X Lion from the Mac App Store. If you have Snow Leopard, click the Apple icon and choose Software Update to install version 10.6.8.
   
3. 

   Step 3: Download OS X Lion from the Mac App Store.

   When OS X Lion is released in July, open the Mac App Store from your Dock to buy and download it. Then follow the onscreen instructions to install Lion.
   
   
   credit: apple.com