Office 365 Small Business Premium supports Windows Vista and Windows XP for most web-based functionality. However, it does not support the download and use of the latest version of Office software, and you cannot substitute Office 2010 for the latest version. You can connect your existing Office 2010 or Office 2007 software to the Office 365 service, but if you are running Windows Vista or Windows XP, you cannot install Office 365 Small Business Premium software, and you cannot replace Office 365 Small Business Premium software with a download of Office 2010.
If you have an active Office 365 Home Premium or Office 365 University subscription, and available installs, you can install Office applications including Word, Excel, PowerPoint and Outlook on your Mac. The applications available for Mac users and the version numbers may be different from those available for Windows users. Customers with an active subscription will always be entitled to the newest versions when available.
Internet access is required to install and activate all the latest releases of Office suites and all Office 365 subscription plans.
For subscription versions of Office including Office 365 Home Premium you will need to go online to manage your subscription account, for example to install Office on other machines, or to change billing options. You will also need to connect to the Internet regularly to keep your version of Office up-to-date and benefit from automatic upgrades.
Internet connectivity is also required to access the Office 365 cloud services such as SkyDrive.
Office 365 Small Business and Office 365 Small Business Premium support a maximum of 25 users.
Office 365 Midsize Business supports a maximum of 300 users.
For 300+ users consider an Enterprise solution, please visit Office 365 Enterprise.