JavaScript validation and form_for

Hi

I have a form I want to prevalidate with a JS function. This doesn't work...

    <% form_for(:applicant,
                :condition => "checkCheckBoxes()",
                :url => { :action => "save_details" }) do |applicant| %>
                      ...
                 <% end %>

:condition doesn't have appear to have any effect unless I use form_remote_for (is this right?)

What's the best way to achieve what I want?

Thanks
Ashley