Practically speaking, I would say that it is a bad idea to give the retail Freespace 2 data to anyone whose primary acquaintance with you falls under the title of 'customer'. It's endangering your business by associating whatever legal repercussions that may result (however unlikely) with that business, meaning if you get in trouble, it could end up harming not only you but the way that you pay for food, etc.
This is because if you start giving away something, it's possible that people will interpret that as a gesture of goodwill ("Oh, he's so nice, he gave me a free game with my network card") which could make them come back to you again, directly resulting in additional profit (for you). Now of course that's not your intention, or at least not the intention you're coming to us with. But it is an effect that it could have on people, and it's an effect that's well recognized in the world of marketing and business.
If you absolutely, positively want to distribute something, I wouldn't really suggest (I don't think distributing FS2 or the engine with a product that you're selling is a good idea) but I would point out that distributing the installer, distributing one of the mods Karajorma mentioned, or just having a poster or desktop background or something where customers can see it would be a little less intrusive. All of these items would not fall under the terms of the license agreement, AFAIK, although anything you distribute with the engine will have the requirement that it not be used for profit, so my second paragraph could still be a problem. And of course, you had better get agreement from whoever's stuff you distribute and get it in writing.
Remember, by law you're giving away someone's intellectual property. If the modmakers discover that people think your network cards are crappy and the modmakers don't want to have their mod associated with your network cards, and the modmakers decide they're going to sue, it will look much better to a court for you to have a piece of writing, showing that the modmaker(s) and you came to an agreement to distribute their mod. Otherwise you don't even have any evidence of good intentions, or of making a good faith effort to contact the copyright holder to obtain the rights to distribute their IP.
(Oh, and I'm not saying your network cards are crappy, I'm just using that as an example of where someone might decide to take legal action against you for giving away their mod.)
Finally, I do want to reiterate that even if you have good intentions in giving away copies of Freespace 2, its commercial affiliation makes it somewhat risky. The legalese of internet projects is also very loose and implicit, since mods do not have their members sign release forms in general. Even if you do get permission from the project lead, I suspect that the individual artists on a project may own enough rights on their individual artwork to cause trouble. Since you're doing this in association with a for-profit enterprise, anything you do with Freespace 2 or FS2_Open or anything related is even more risky, because you're jeopardizing your welfare as well as the business and making it more official (dare I say, institutionalizing it) by associating it in connection with business products and customers, and not just as something that you as an individual seems cool.
So, I'd like to see Freespace 2 get more publicity, but I think that doing it the way you're suggesting has a chance of attracting the wrong kind of attention.
DISCLAIMER: I am not a lawyer. I've read one book that loosely touched on marketing, and the first 80 pages or so of a legal book for independent filmmaking. I do not have any professional experience offering legal counsel and I encourage you to research this topic yourself.
