For PC users:
Minimum systems requirements for Office 365 are the following on your PC: XP operating system with SP3; Office 2007; and Internet Explorer 7. You can find full requirements here.
For Mac users:
Minimum system requirements for Office 365 are the following on your Mac: Mac OS X 10.5 (Leopard); Office 2008 for Mac & Entourage 2008 Web Services Edition; Safari 4 or above.
Contact us if you are not sure about meeting the system requirements.