Converting .flv files to .mp4

I have a bunch of movies I've downloaded on my computer, but some of them are.flv files. If I were to burn one of those files to a dvd, would it work the same is if I had burned an mp4, avi, etc.? And I've converted some of them to mp4 already, but after it was finished there was no sound?

I am trying to convert my videos into flv so that I can upload it to blip real easily. But I would like to know what the best width and height for my videos so that I can fit it in. What is the best width and height of the blip videos?

Is it possible to play .avi in mobile using some softwares? If anything of such sort exists, please provide the link in your answer.. I prefer freeware.
My cell phone is Micromax Q5 fb(screen resolution 320*240), it supports only Java J2ME.

i need a free, absolutely free, no watermark, no trial version, software that converts vts to mp4 so that it can be played on the psp. i have tried handbrake, can't figure out how to make it work. have tried Xvid4psp, and many others. help me out here. and don't say pspvideo9. that obviously dosn't work with multiple vts files.

i have 10 video files .mp4, and i need cto compress that data not by converting to other codecs but by using convensional compression tools like 7z, paq, uharc...

i already tried with those 3 compression methods but at the end i get a max. compression ratio of 98% using 7z at ultra configuration.

so my question is if you know abut other compression methods wich could give a better compression ratio for this kind of data.

i dont care about memory usage or processor usage, i have an i7 and 4gb ram.

but when i transfer the file it is only 3 minutes long. it does this for every movi。