Vicktor,
Uhm... - actually I do work at a large company. Usage of OpenSource is not a question of the company size, but of the company management.
I think you will find in most companies its about the cost of maintenance. As with commercial solutions there are good Opensource projects, apache for example, and bad opensource projects, sendmail for example. Ultimately its about finding the good and the bad and ensuring that you have capabilities to support and maintain this at a cost that is acceptable to your customers. People who believe that they 200 line perl script is a cheap way of doing something have an incredibly short sighted view, sometimes it does, somestimes it doesn't. Management clue and confidence is another issue, one of the reasons I went into management was to try and spread clue.
In my first company we exclusively ran everything as cheap as we could, we thought that opensource was the answer, it was 1992, we had GateD running on NetBSD 0.9 talking BGP4. Our mail platforms were all opensource based. We had developed our own cheap modem bank solution based on free software and perl. However we soon found out that to keep all these solutions going and growing required hundreds of people to maintain code, do testing, add features. We bought a couple of Ascend Max4000s [first in Europe to get them] and we were able to cut our costs by almost 60%. On usenet we bought Cyclone and every single issue we had with Usenet went away +overnight+.
These were not the only examples and our GateD route solution helped us to avoid spending millions on Cisco gear. That company is still running but now suffers a lot of it because of our homebrew solutions not scaling.
However I understand the managers... OpenSource developers don't invite managers to a weekend in a mountain wellness resort, offer them free drinks at events or give you expensive gifts. Commercial Software companies do it all the time...
The most I've ever got was a mouse mat - which vendors are you using? I want some of this goodness :D
Regards, Neil.