The comment below about Speed Download is a worthwhile warning. Speed Download is one of the relative handful of programs mentioned in the included read-me which include code to determine whether the executable file (not the code, but the file itself) has been modified and then refuse to perform their normal function if any change is detected. I'll restate for clarification: The corrupted executable message you'll see is coming from SD itself. It's not the OS reporting that there's actually anything damaged about the program; it's SD acting exactly as the developer designed it to act.

This behavior has never been recommended or supported by Apple because there are circumstances under which the OS itself will modify an executable and any app doing this will "break" even for that.

Version 0.6 added a "safe trim" mode which is enabled by default precisely because of applications like this. Version 0.7 will include a "blacklist" feature that prevents it from trying to trim apps that are known to do this.

In the particular case of Speed Download, it should be noted that the developer has made a PPC-only build available for download at http://yazsoft.com/files/sd3018ppc.zip. There's no native-only option for Intel users at this point.