If you don't know which version of the game you have, it's fairly easy to find out. 

If you bought it in retail store and/or have an actual box, you have the retail version. 

Otherwise to check which version you have, just start the game and check some things on the first screen.

If you don't have the Visit Website menu option, then you have the Reflexive version and need to grab the latest version from them.

If there is an Arcade Town logo in the lower right side above the Soldak logo, then you have the Arcade Town version and need to grab the latest version from them.

Off hand I'm not sure how to check if you have the TotalGaming.net/Impulse or Gamer's Gate versions but you probably already know in these 2 cases.  The Visit Website button probably points to their sites though.

Otherwise, it is our version of the game and you can use our patches.