Earlier this year, I dealt with a small company with three users. They also had three servers:
The services were split across three machines to spread risks. Through their firewall, only the web server was fully visible from the Internet, whilst the mail server was visible from an off-site mail forwarder. The file server was not at all visible from the Internet.
Because Microsoft will be withdrawing support for NT4 Server, they had to consider upgrading at some point over the next year. The O/S on the servers would need to go up to Windows Server 2003, which itself has considerable cost. In addition, the first two servers would under no circumstances be capable of running this. The third would probably be able to, but was below the minimum recommended configuration. Upgrading to Windows Server 2003 would require them to buy three new servers. In addition to this, Exchange 5.5 and SQL Server 7.0 would not run on the new O/S, so these would need to be upgraded as well. The cost of this was getting close to £10K, without even considering the costs of technical assistance to make this move. The new software would give them a lot of new functionality, but they did not need it. They were very happy with the NT4-based solution, which did not requre a lot of maintenance. The new functionality also comes with a larger risks of 'vulnerabilities' (a.k.a. bugs), so they would need to start looking very seriously at continuous patch management.
For just three users the cost of upgrading was simply not justifiable. But the risk of not upgrading was that if new vulnerabilities were to be found in their current software, they would not be able to protect themselves, as Microsoft will not be developing patches for NT4 after support is withdrawn.
Although this was not a tech company, the system administrator was a teach-savvy lady, who had used Unix a little bit whilst she was at University in the early eighties. She had not thought of using Linux for their current environment, but after I mentioned it, she was willing to consider the idea. We proposed migrating the three servers to Red Hat 8.0. This runs fine on the existing hardware and has no software costs. The web server was to become Apache, whilst file and print services were going to be delivered with Samba, both of which are free. Exchange was replaced with Samsung Contact and SQL Server was replaced with ProgresSQL, also at no cost (Samsung Contact is a closed source product, but can be used for free with up to five users). The total software/hardware cost of this migration plan was therefore £0.00. The only cost they had was two days of consulting from myself.
After migrating, the company also found that their servers had better performance, were much more stable and required much less attention overall, allowing their system administrator to focus more on her main job.
I had a call from her yesterday: What would it take to move their Windows 2000 desktops to Linux as well?