BEcause there is no answer to my first problem I'll try to explain it simple.
Please someone to test it. Install your winamp in differnt folder then $PROGRAMFILES\Winamp. Run some older installation and you will see that it detect exactly this folder thet you install WINAMP for last time not your first folder. Then make some NSIS script with new NSIS and you will see that it do not detect it. Is this to you.

Here is string I use for detecting default install folder:
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InstallDir $PROGRAMFILES\Winamp
InstallDirRegKey HKEY_LOCAL_MACHINE SOFTWARE\WINAMP ""
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This string find only $PROGRAMFILES folder and do not find changed WINAMP folder (this is only for NEW NSIS versions from 1.1k older like 1.1j works fine)
May be I do something wrong. May be I do not use proper RegKey. Because this is something new older verion do not have this. Thay automaticly find proper folder. WHATS HAPPEND ? HELPPPP!!!!!! :-)

Tonic