Computer Aid International has shipped 200,000 PCs and laptops to schools, hospitals and charities in developing countries since it was established in 1998.
The PCs have been donated by individuals and organisations across the UK, including a number of big name businesses.
The PCs are now being used by not-for-profit organisations to improve education, health and agricultural production in very poor and rural communities across 112 countries.
Tom Butcher, external relations manager at The Met Office, said: "Our donated PCs to Computer Aid have helped National Meteorological Services in Kenya, Uganda and Zambia to digitise weather observations which are used to help rural communities make better weather dependant decisions."
This type of weather information helps farmers to decide when to plant their crops and which varieties or combinations of crops to plant to secure the best yields possible. Poor crop yields can have a devastating and long term impact on a farmer's livelihood as well as food security for an entire community.
Sainsbury's is Computer Aid's largest PC donor to date, having donated over 11,000 items of equipment over the past three years. Neil Morgan, team lead for IT and logistics at the supermarket chain, said: "It has been a win/win solution for both of us, as Computer Aid made donating the computers extremely straight forward by carrying out secure data-wiping of the hard drives, taking full legal liability and allowing us to deliver large volumes of equipment."
Computer Aid has appealed for another 50,000 PCs to be donated this year.
Earlier this year the charity expressed disappointment at a lack of emphasis on reuse of technology in an updated version of the European Waste Electrical and Electronic Equipment (WEEE) directive.