ml_news@ddnospamddml1dd.co.uk.dd says...

This FAQ is a difficult one to answer accurately yet concisely and in an understandable way... Would you like to script your take on what you've found?

My answer would be -

"There is not significant additional strain in any circumstance.  Traditionaly,  computers execute an idle loop to keep them busy all the time anyway. Computers with power saving features (usually laptops) will work slightly harder since the power saving features will not work when running SETI@home."

Yes the answer might cause people a bit more stress but it's more honest.