The National Security Agency, responsible for protecting United States government communications and information systems, has released a informational datasheet advising Windows XP users to migrate to Windows Vista or Windows 7 as soon as possible.
In a datasheet titled "Best Practices for Keeping Your Home Network Secure", the NSA is urging users to migrate to a modern operating system, modern hardware platform, and latest software versions to increase your security.
Both Windows 7 and Vista provide substantial security enhancements over earlier Windows workstation operating systems such as XP. Many of these security features are enabled by default and help prevent many common attack vectors. In addition, implementing the 64-bit mode of the OS on a 64-bit hardware platform substantially increases the effort of an adversary to attain a system or root compromise. For any Windows-based OS, verify that Windows Update is configured to provide updates automatically.
The NSA also recommends that users upgrade to the latest version of Microsoft's Office productivity suite, or at least use a version greater than Office 2007.
If using Microsoft Office products for email, word processing, spreadsheets, presentations, or database applications, upgrade to Office 2007 or later and its XML format for storing documents. By default, the XML file formats do not execute embedded code when opened within Office 2007 or later products thereby protecting the user from malicious code delivered via Office documents. The Office 2010 suite also provides "Protected View" mode which opens documents in read-only mode thereby potentially minimizing the impact of a malicious file.
You can download the full datasheet (PDF) here. It also contains various valuable information regarding iPad security, Mac OS security, data encryption, and web-browsing safety.