Personally, I can't stand XP. It's older than sin, it's clunky, and the UI is outdated and ugly.
Who gives a damn? XP is rock solid, fast, it WORKS - and Microsoft will officially support it until 2014. So it's still a safe bet to use XP and for most users -- including users who do VERY "techy" stuff -- there absolutely is no reason to upgrade to a newer version of Windows.
By 2014, Windows XP alone will have had a longer life than all versions of OS X. All the people who talk so much about Apple's "outstanding support" should think about that for a minute before they go on bashing Microsoft and PC vendors. Apples makes their operating systems - and hardware - faster obsolete than Microsoft releases Service Packs. If you want longevity, choose a PC with a Microsoft OS.