Much as I’m personally not a huge fan of Microsoft software, it is fairly much the standard in work environments around the world and what people are used to. For registered and recognised charities in Ireland (and probably most anywhere else), organisations can get up to fifty installations of Windows Professional, MS Office Pro Plus and many other items of Microsoft software for between 4% and 8% of their full price. In the Republic of Ireland the software can be ordered through ENCLUDEit and in Northern Ireland through CTX.
If you want to go completely online or a mix of both, you can get Office 365 for free by applying directly to Microsoft for unlimited licences for your organisation with the Nonprofit E1 (online applications only) or heavily discounted Nonprofit E3 that gives you both the online applications and infrastructure along with installable applications for local machines. Find out more at microsoft.com.