how to manage errors in ARes?

how to manage errors in ARes?
Hey all,

I have that function:

def create
    @profile =[:profile])

    respond_to do |format|
        flash[:notice] = 'Profile was successfully created.'
        format.html { redirect_to profile_url(@profile) }
        format.xml { head :created, :location => profile_url(@profile) }
        format.html { render :action => "new" }
        format.xml { render :xml => @profile.errors.to_xml }

Now when I create a profile from ARes with wrong information, I don't
get the same error I would get normally. I only get some http errors,
not the activeRecord ones, isn't @profile.errors.to_xml supposed to
send me the ActiveRecord errors? if yes, how can I get that errors.xml

Thanx in advance