<A target="_blank" href="http://www.pcworld.com/article/181165/windows_7_64bit_users_living_in_a_32bit_world.html?tk=rss_main">WinXP came in 32-bit and 64-bit varieties. Same OS, built to run</A> on different hardware. That was almost 6 years ago. Win7 is also being offered in 32 and 64-bit versions, but applications are still being offered mainly in 32-bit versions.