There have been a few discussions on train catalog software, you can try a search for something along the lines of train inventory or train catalog or just software and some they should turn up. I would offer some links, but I can't remember any specific threads.
I think the general consensus was people mostly use Excel to track their trains, a few use Filemaker or Access or something else they have created themselves. I have looked at a few specific programs for this purpose and RR Trains 2000, Yard Office and Easy Model Railroad Inventory looked promising, but didn't really do all that I wanted them to do so I ended up using Filemaker. I am not completely happy with my own either, but I keep fiddling with it and it is getting better little by little, maybe someday...
You might take a look at RR Trains 2000, Yard Office and Easy Model Railroad Inventory, they were all fairly nice programs, one may be just right for you. If you find some of the other threads here on the forum, there may have been some others mentioned, but I can't really remember if anyone really liked any of them?