Comment by hsitz

Meaning is the same for 'fora' and 'forums', but both are fine and 'forums' is in fact more commonly used: http://grammarist.com/usage/fora-forums/

I suspect same is true for viri/viruses and formulae/formulas but I'm not even worried enough about to check. Me saying 'viri' or 'formulae' would be me being a person I don't want to be.