Just imagine you are writting in roman urdu and its automaticaly converting in real urdu. OMG its real. you can write urdu very easily. Google Inc launched Google Indic Transliteration which can done this work in seconds

http://www.google.com/transliterate/indic/Urdu

جی ہاں اب آپ اردو میں با آسانی لکھ سکتے ہیں ، ضرور ٹرا ے کریں