Network World's recently-released NW200 - which lists the top 200 vendors in the network industry, by revenue - was again fairly light on Linux companies this year. This is probably what you get for selling a product that can be downloaded for free; however, companies that use Linux as a major part of their business strategy did quite well.Red Hat - probably the only true vendor among the NW200 that could call itself a Linux company - jumped from No. 134 on the list up to No. 116. The company posted $257 million in revenue last year, a 45% gain on the year before. Meanwhile, Novell - which is now a partial Linux company, thanks to its SuSE division - slipped from No. 59 to 61; it posted almost $1.2 billion in revenue last year, a 3% dip from 2004.Among the IT vendors that make billions off of selling Linux-based servers - IBM, HP and Dell - these vendors each ranked No. 2, 3 and 5, on the list respectively. While Linux makes up a small portion of each of these vendors multibillion-dollar sales figures, they are among the most vocal in terms of pushing Linux products into enterprise data centers.Incidentally, two start-ups that made the NW200 "10 Start-ups to Watch List" come to market with strong Linux technology backgrounds. Centeris of Bellevue, Wash., makes a product called Likewise, which allows administrators to manage and configure Linux servers through a management interface on a Windows workstation. The software also lets Linux boxes join Microsoft Active Directory structures.BlueNote Networks, a Tewksbury, Mass.-based VoIP start-up, makes a product called SessionSuite, which runs exclusively on Red Hat Linux servers. The vendor's software is a modular, SOA-based IP telephony platform that runs messaging, call control and other communications apps as XML-based services on the network.