Lots of big companies have been behind Linux for years, money is not the issue.
The issue sadly is the people - some very talented programmers are crippled by a belief that the command line is better, that being able to edit options from drop-downs on a nice menu rather than with command line switches is for morons, that nice click-through installers for drivers are useless compared to a nice long script etc etc.
What Linux needs to succeed is to be useable for everyone, regardless of ability. It also needs to run the software people want to run. You have to remember the average joe will NEVER understand why their piece of PC software will not work on their PC. The Web will gradually mean that a stripped down OS to run browser apps could be a success, that is what Google thinks anyway.
For business Linux already has some nice little markets, but for the business desktop it needs to make life much easier for admins, with simple graphical tools for everything. Linux actually has some advantages here as the command line is so much more powerful for scripting etc, but where is its market for the corporate desktop, the SME? How does it break in?