How are you tax credits and standard rate cut off points allocated at the moment?
It sounds as if there's no point in her transferring her personal tax credit to you (as her gross salary for 2010 will exceed €18,300).
As her gross salary for the year should be less than €27,400, there should be merit in you taking the higher standard rate cut off point of €45,400. She'll then get a standard rate cut off point of her gross salary (which should be circa €24,000).