Audio File Converting

I was wondering what program or format i should save audio files as for best quality.

Ive just been using Goldwave to convert them to 48k sample rate and a 320k bit rate in .mp3 format.

Recently, my friend said he used Nero to digitise his songs (i thought was wierd), but non the less it improved the quality. The only better thing i can find with nero is a 400k bit rate for .aac format and 500k for .ogg.

would these give such a drastic improvement?