If you want to use Windows XP after the end of support deadline, then Windows Embedded POSReady 2009 might be worth a look. It's basically Windows XP SP3 but modified for use on Point of Sales systems. Since it has roots in Windows XP, it can run most (if not all) XP supported programs. It also has extended support from Microsoft until 2019!
ISO: http://www.microsoft.com/en-us/download/details.aspx?id=11196 Product Key: (removed because of possible legal issues)
Music/Credits: Intro music: Approaching Nirvana - Even While Buy on iTunes: http://bit.ly/v1isq8 Background/Outro music: http://www.incompetech.com Intro created by: http://www.youtube.com/user/airmagine