[Lazarusxx]

This litho is indeed the first in the series - after the first three the images have been contracted out to specific artists, and as such have become less of a collectors item, regardless of the fact that they're numbered.
You can tell that this is the first in the litho series because the "Fallout" logo in the bottom left corner is filled in with colour, where as the following lithos (The Monument, The Capitol and Ashes of Megaton) were text only. You have a nice frame on your litho, I hope you paid the extra for the archival glass to keep the colour long lasting, because as Fox said, they will be more difficult to find down the road.

On a side note, I've been documenting (in picture, and limited text form) all the collectibles for the Fallout universe, both official and unofficial, promotional and commercial through a collector's group on Facebook. If you are interested in joining our small but growing community, please message me with your Facebook info so I can add you. Only members can find us but if you are looking for a group with specific knowledge on the Fallout collectible sphere, I would say that we are the place to be. Of course, I may be a little biased since I helped found the group ;-)