Converter for AAC and MPEG-4

[official]

How to convert the mp3 files to aac format and how to make mpeg-4 files

[teknoPhobia]

The latest Nokia PC suite has an excellent converter built in

[Pathik]

xilisoft converter..

[pops]

Nokia PC suite (Nokia Phone Manager) is just fine…
If u want to convert offline!!! u may try dBPowerAMP.
hxxp://www.dbpoweramp.com/dmc.htm
It is one of the most easiest way.

If u are power user U must try “Easy CD-DA Extractor” which has the ability to switch between different codeing technology like aacPlus v1(SBR) and aacPlus v2(SBR+PS) etc.
hxxp://www.poikosoft.com/

And for video MPEG-4 u may Try Nero Vision (*.mp4) or DivX Converter (*.divx) for better picture quality. For better control over output files u can try Dr.Divx. for more Inf switch to:
hxxp://sourceforge.net/projects/drdivx