Make sure that you are using a 32 bits wineprefix or windows installation (aka WINEARCH=win32)
What wine version are you using? Try wine stable 1.6.2 or one of the latest 1.7.x releases.
I am using Sabayon with wine-1.7.33 (Staging) and MTA works fine except for some font artifacts/glitches on MTA, e.g. chat.
I am also using a ubuntu based distro wine wine-1.6.2 and also MTA works fine, and without font glitches