Quite some time ago, Microsoft published the "Life Cycle" for their products. The information for all software, games, tools, hardware is available in Product Life Cycle, which is reviewed and updated regularly.
In January of this year, Microsoft announced that support was extended from September to October for XP Service Pack 1 (SP1) and 1a (SP1a). As published in Microsoft Help and Support:
Windows XP SP1 and SP1a support ends on October 10, 2006Service Pack 2 (SP2) for Microsoft's XP Operating system was released two yearsago. SP2 included significant security enhancements. So why is it a surprise that support for SP1 and SP1a is ending? Why is it that I am still seeing countless logs in the forums either without any service pack installed or still at SP1? There is no time to delay. Information on updating to XP SP2 is available at the link below.
Support for Microsoft Windows XP Service Pack 1 (SP1) and Service Pack 1a (SP1a) ends on October 10, 2006. Microsoft will end support on this date. This also includes security updates for these service packs. Microsoft is providing final notifications to customers regarding the end of support for these products.
Please don't delay.
The SP2 upgrade is free and includes not only enhancements to the XP operating system but, more importantly, it incorporates better protection against viruses, hackers, and worms than SP1 and SP1a.
XP SP2 Update Information
Order Windows XP SP2 on CD