The legal shadow hanging over Linux is a major factor imho. When this is cleared up, or at least there is a bit more visibility, I think alot of corporate IT managers who are on the sidelines will dip the proverbial toe into Linux (or to come out of the closet on their current deployments). The enterprise service and support products from Red Hat and SUSE are really quite compelling, at least server side. Seriously, how many people do you know who are truly happy with say MS IIS or Exchange?
The "Legal shadow" isn't there.
Novell (among others) has offered legal idemnification to those running SuSE. That means that Novell would pay the legal bills, etc should things go wrong in the copyright wars.
What shadow there is is caused by a lawsuit from SCO. The money to sue Novell, IBM, DCX and AutoZone AT THE SAME TIME comes from a venture capital company that was "introduced" by Micro$oft to SCO.
You wanna try Groupwise 6.5 on a SuSE SLES9 box? I'll make sure you get the trial software....
Litigation isn't scaring anybody off. Prices to enterprise customers are negotiable of course, but for the most part Windows is less expensive than Windows. You can't impress me with TCO either. In my outfit, Windows server support runs a 150:1 ratio servers to FTEs. UNIX/Linux support, on the other hand, runs about 60:1.
Linux is a great OS with a place in the data center. Linux will destroy Sun, then certain flavors of Unix. After that, it may be mature enough to challenge Windows for general purpose file/print/application serving.
Check this out, How SCO's Threats Rallied Linux