How to change language in Photoshop CS5 from Polish (or any else) to English? (Windows) [locked]

Hi,

I have a Polish language version of Photoshop CS 5 and I'd like to change it to english.

I've tried by

Edit>Preferences>Interface: Interface language

but there is only Polish language to choose.

Is there english version to download anywhere?

I'll be glad for any help

[This question is from January 3, 2012 about CS5. The correct answer for CS5 is no, you have to buy a new version. This thread is now locked, and the answer has changed in newer versions.]