No. But she would need to create a Microsoft account (https://signup.live.com) that she can register with her existing email id (be it with outlook.com/hotmail, gmail, yahoo, work email etc).
Microsoft account is mandatory for Windows Phone if you need to download apps from the Windows Phone Store.
Edit - Each to their own but I would strongly suggest looking at Nokia's range of Windows Phone. App support and software update support (firmware updates etc) is a LOT better than Samsung or HTC in the Windows Phone ecosystem.
Nokia Lumia 920, Nokia Lumia 720 (available from TheWarehouse or expansys.co.nz), Nokia Lumia 620 (Noel Leeming) and Nokia Lumia 520 (Telecom, Vodafone NZ) are the best one's to go for.