What is the correct format/resolutoin for videos on an HTC Wildfire?

i currently own a HTC Wildfire. I am well aware of its "lower" CPU speed than its HTC brothers, nevertheless, it is a great phone and I'm very happy with it.

I tried putting a mp4/m4p video (around 330mb) and the built-in video player crashed.

Can anyone guide me on the correct format/resolution I can use on this phone? Additionally, if I do have to convert an existing video, what software do I use?

I appreciate all inputs, thanks!