I just got the Spellforce edition and it looks like i cant install it because the files seems too be corrupted, i downloaded the 3 parts and tried installing them, anybody knows how to fix this?

I take it you mean you downloaded with a browser. I would recommend is trying to download it with the GOG Downloader which features error-checking.

If you want to check the files you already have and download the broken file again, the GOGWiki page has MD5 Hashes for each of the parts. WinMD5Sum is a free utility that should work to check the hashes. If they match, the file is good.

And in case the solution above doesn't work, try disabling your AV while downloading and installing the game.