Thank you for your interest plukie. I understand in this day and age we have to be careful about what we download from the internet. I have found some information about security on their website if you use this link it will take you straight to it
http://www.grid.org/help/faq_security.htm
I can not guarantee the safety because I do not have enough knowledge of computers to do this but I have been running this program for 18 months and my computer has now donated 206 days of time. If you go the team you can check my details to see that this is true. My UD name is shelley_845211 you will automatically view my information since I joined the team but if you click on my name it should give you my history. My parents have been running the program for even longer. It was through them that I learnt of this site.
Any queries you can always PM me.
Thank you again for your interest.
Shells