I think (And I could be wrong, so don't take my word on it.) that the 'The Warzone 2100 Resurrection Project' version is legal.
As a rule downloading ripped version of a games CDs is definitely questionable/illegal. The game becoming Open Source does not automatically mean all previous releases are free. So I'd be careful about downloading anything from a site with 'the pirate bay' in its web address name.
If this CD version still contains the FMVs then it is definitely illegal, since the cut scenes have not be release via open source. (From what I've read.)
The Warzone 2100 Resurrection Project:
Although the 'Resurrection Project' version seems to be ok. I'd do some more independent research before downloading it just in case. (Like find the official copyright holders site, if it still exists, and check to make sure they've released it as open source.)In late 2004 Warzone was released by its copyright holders, Eidos-Interactive™, to the public under the GNU General Public License (GPL) (minus the FMVs)
I played this game when it came out on the PS1, it was pretty good!
Sorry about the rant.