form_tag validation

Hi,

I'm writing a Rails 2.3.2 app and am using form_tag and trying to
figure out the best way to perform validation, and on failure I want
to display the errors back to the user just as with ActiveRecord,
except this form is for contact purpose and does not have a table in
the back.

I've looked around and found the Tableless ActiveRecord which is
apparently deprecated, and the ActiveForm, which seems pretty good,
except that it seems to be idle since 2008 as I see. Can I rely on it,
or am I gonna end up changing lot of code soon after we move to Rails
3? What's the best way to do it?

Thanks