Hello to everybody! I'm interested which codec is best for decoding, from mp3 to wav? Second, das quality(wav) is gonna be same if i decoding from mp3 with 320 bitrate or from 128 bitrate?

Hello at the forum!

Decoder commonly regarded as "The Best" is the one included with Foobar2000.
If you're looking for GNU/Linux, Unix, whateverOS one (I guess you aren't), then try MAD.
Unfortunately MAD sometimes clips the end of the file.
Fraunhoffer decoders (e.g. Winamp) are very good too, though they don't employ dithering to slightly increase quality and don't support 24bit soundcards (no, Audigy1 doesn't support 24bit playback).

No decode from any MP3 will have exactly same quality as Wave file.
That's why it is called LOSSY encoding. All lossy encoders try to lose quality,
so that the loss is inaudible, but most of them fail this task (at least on some problem samples).

Theoretically, higher bitrate equals higher quality of decoded file.
But there are poor (old Xing, ISO) and good (LAME, FhG) encoders.
The 320kbps file from old Xing might sound worse
than a file properly (using switch --alt-preset) encoded by LAME.

/EDIT\: Slight rewording to not look like FB2k fanatic. /EDIT\