If you are still running a PC with Windows XP and have not yet updated it beyond the first service pack, you now have a new incentive to do so. Computer and Video Games reports that Valve will stop offering support for PC with Windows XP SP1 for its Steam game download service after August 31st.
The main reason for the support cut off is sheer numbers. According to a statement from Valve, ""Our data shows less than 1 percent of those on Steam are running XP Service Pack 1." Basically, if you are running that version of Microsoft's OS, you should go ahead and download the SP 2 update ASAP if you want to continue using Steam to download and play games, or better yet update completely to Windows 7.
Microsoft has been issuing a number of warnings for some time that it will be shutting down official support for Windows XP as a whole in the near future. The official support cut off date is April 8, 2014. Even with this deadline looming, Windows XP is still the most used PC operating system worldwide. The latest data from Net Applications claims that Windows XP is in use in 44.85 percent of the world's PCs.
Source: Computer and Video Games