If the plan is to install Windows 7 onto the same machine that was running XP, you'll need to determine whether it's powerful enough to run Windows 7. We believe that the target machine should have at least an Intel Core 2 or 64-bit dual-core equivalent AMD processor running at a minimum of 1GHz, plus 4 GB of RAM and about 20 GB of available hard drive space. A Core 2 or later also will permit virtualization, but add another 20 GB of storage. Microsoft's system requirements for Windows 7 are a bit less stringent. To help with planning, Redmond recommends a visit to its Upgrade Advisor Page for guidance on app compatibility and links to hardware drivers and to Upgrade Advisor, a free utility that scans the hardware for possible migration issues.