XP includes slightly redesigned Graphical User Interface features, some of which appear to have been inspired by modern Linux [desktop environment]?s such as KDE. The graphical login screen with user images is one such feature.
It also includes somewhat enhanced security features such as an integrated firewall, which were probably included partially due to increasing competition from Linux. It is also part of an overall effort to secure the operating system after general dissatisfaction with its history of security vulnerabilities.
XP has come under intense criticism and scrutiny due to the integration of many user applications for which there has traditionally been a thriving third party market, such as the firewall and [Windows Media Player]?, as well as its close tying to the [Microsoft Passport]? network which is seen by many computer experts as a security risk and threat to privacy. These features are also widely believed to be a continuance of Microsoft's anticompetitive? behavior.
It has also been sharply criticized for its product activation scheme. This takes an audit of certain components on the host computer, creating a unique reference number that is logged by Microsoft before the software can be used permanently (it comes with a 30 day activation period). Installing the software on another computer would generate a different number that would not match the one stored by Microsoft. This would prevent a new license being issued, disabling the software.