Does anyone know of any FREE software on the net that will allow me to convert files into 3gp or even mp4 if need be, in order for them to play on my mobile phone?

Safe

Google for "Videora", as they do ipod (mp4) *and* 3gp software, and it's completely free

i have mobile 3gp convertor from miksoft installed but i only use it for converting FROM 3gp not sure if it does it the other way, look on their website their might be another convertor
http://www.miksoft.net/