http://bugs.winehq.org/show_bug.cgi?id=21097
--- Comment #19 from Michael Kanis mkanis@gmx.de 2011-03-18 09:50:13 CDT --- Eduardo, from what I understand your guess is absolutely correct. You would need the 32bit version of libtxc_dxtn.so. You will also need a very recent version of the radeon driver or use r600c (see [1]). I didn't test this yet though, because I'm too lazy. ;-)
[1] http://www.phoronix.com/scan.php?page=news_item&px=OTEwNg