What you need

To install Lion, you need a Mac with a minimum of 2GB of RAM and one of the following Intel processors: Intel Core 2 Duo, i3, i5, i7, or Xeon--early Intel-based Macs with Core Solo or Core Duo processors aren't eligible. You can determine your Mac's processor and the amount of installed RAM by choosing About This Mac from the Apple menu and looking at the Processor and Memory lines, respectively.

Apple's system requirements also state that "Some features may have additional system requirements." We're assuming Apple is referring to graphics cards, as some graphics-heavy features require more horsepower than the oldest Lion-compatible Macs provide(mac software: mac video converter).

Finally, there's also a software requirement for installing Lion: Your Mac must be running Snow Leopard (Mac OS X 10.6) v10.6.6 or later. In addition, Apple recommends that you have the very latest version of Snow Leopard before installing Lion, so be sure to check Software Update for any available updates.

Pre-install tasks

While Apple portrays the process of upgrading to Lion as a simple "download and install," those of us who've been around the block a few times know that a major OS update is never that simple. Perform these tasks before the upgrade and your chances of a pain-free experience will increase substantially.

Make sure your Mac's startup drive is in good health: To do so, open Disk Utility (in /Applications/Utilities), select your startup drive, click the First Aid tab, and then click Verify. If Disk Utility finds problems, you'll need to boot from a different volume to perform the actual repairs using the Repair Disk button. If you've got access to either your Snow Leopard Install DVD or the OS X install DVD or thumb drive that shipped with your Mac(flv converter mac), you can use that. Alternatively, once Lion is released, you can create a bootable Lion installer volume--stay tuned for those instructions--and boot from it, as the installer includes Disk Utility. If you're feeling especially cautious, you can also opt to run Apple Hardware Test.

Back up your Mac, and test that backup: Let me say that again: Back up your Mac, and test that backup, before installing Lion. I personally recommend creating a bootable-clone backup--I use SuperDuper for the task, although a Time Machine backup will do as well. To test a clone or other bootable backup, use the Startup Disk pane of System Preferences to boot from the backup drive. To test a Time Machine or other non-bootable backup, try restoring several files to make sure the process works.

Run Software Update: To to be sure you're running both the latest version of Mac OS X--version 10.6.8, for example, included fixes specifically for the Mac App Store in preparation for Lion's release--and the latest versions of any other Apple software that might be affected by Lion, you should run Software Update. You should also check for updated firmware for your particular Mac model.

Disable FileVault: If you're using FileVault, OS X's built-in account-encryption feature, on any of your Mac's accounts, I recommend disabling FileVault before upgrading to Lion. Why? For one thing, Lion uses a different approach to encryption, and while Apple says you can keep using the Snow Leopard implementation for previously-encrypted user accounts, Lion's approach is likely the better way to go. Plus, I prefer to not test Murphy's Law by risking any incompatibilities between the two versions of FileVault. Similarly, if you're using third-party disk encryption, you should probably disable that before installing Lion.

Check for Lion-compatible updates to third-party software: As with any major upgrade to Mac OS X, you'll likely find that some of your third-party software needs to be updated to work with Lion. If you take some time to check compatibility before installing Lion, you'll be in a position to get up and running immediately, rather than being frustrated by your favorite apps and add-ons not working. Especially useful for this task is RoaringApps' growing list of Mac software(video capture for mac) and Lion compatibility.

Prepare an extra drive handy: While most people will simply install Lion over Snow Leopard, there are situations in which you might want to install onto an empty drive. For example, if you want to install Lion on a second drive to test the OS before upgrading your "production" drive, or if you want to erase your Mac's startup drive and start anew. As we'll cover in our upcoming article on installing Lion, installing onto a secondary drive is simple. However, erasing your Mac's startup drive and starting fresh means having a good, tested backup as well as a bootable Lion install drive, so now's the time to start preparing.

Ready and waiting

Thanks to Lion's Mac App Store distribution, the process of purchasing, obtaining, and installing Mac OS X should be faster and easier than ever--at least for most people. But it's always good to be prepared, because the better shape your Mac is in before the upgrade, the better experience you'll have afterwards. Now that your Mac is properly prepped, stay tuned to Macworld--once Lion hits the streets, we'll have a slew of articles on installing and tweaking the new OS. (Source: itworld)