Did you use the nokia software or some other software? Is the phone cutting down the video or is the software? I seem to think that I might have had a problem with that but I can't quite remember. I have not done alot of converting or stored alot of mpeg's on the phone yet.The ones that I have stored on the micro sd card that I bought have played the full video on the phone.
If you are using the nokia software to convert when you select save as and when the window comes up go to resolution and Size limit box and set that to no limit 176*144. It will convert the whole video. I think this is what I was doing at first but figured it out later but forgot to tell you that part-Sorry.