Before You Start Install Windows 7
Programs originally written for earlier versions of Windows (including Windows XP and Windows Vista) might not run properly under Windows 7. Likewise, some older hardware devices require drivers that have never been updated for use with Windows 7. The worst possible time to find out about either type of compatibility problem is right after you complete a fresh installation of Windows 7, when you try to use a favorite program or device.
To spare yourself unnecessary headaches, if the computer on which you plan to install Windows 7 is currently running Windows XP (with Service Pack 2 or later) or any edition of Windows Vista that you are planning to upgrade, download and run the free Windows 7 Upgrade Advisor first. This tool, available from w7io.com/0201, scans installed programs and devices and produces a report identifying any potential issues you're likely to confront as part of an upgrade.
The purpose of the Upgrade Advisor (which was available only in a prerelease version at the time we wrote this) is to identify hardware and software issues that might interfere with your ability to install Windows 7 or programs that might not run properly after the upgrade is complete.
Use dynamic updates
When you upgrade over an existing Windows version, the setup program offers to check for dynamic updates. If you have an active internet connection, be sure to take advantage of this option. Dynamic updates can include any or all of the following: critical updates to the setup program itself; improved or new versions of boot-critical drivers for storage, display, and network hardware detected on your system; and compatibility updates (also known as shims) for programs you're currently running. Rolling these updates in at the beginning of the process increases the likelihood that the Windows 7 setup will run correctly. After completing installation, you'll still need to connect to Windows Update to download critical updates for Windows and the most recent drivers for detected hardware.