For small companies involved on IT projects, reducing costs (expecially on
hardware and software licensing) is estremely important, but this "costs
cutting" must always be well evaluated in all aspects because a bad choice
(maybe only for reducing the costs of few dollars) could be a big disaster on
the near future for your project.
This consideration comes from a question
I've see today on our User Group (but it's not the first time that I see
something like this): a company have to place its newly created ASP.NET
portal in production and, in order to reduce the costs, its PM suggest to use
Windows XP to host the site instead of Windows 2003. 
I don't want to know what are the background skills of this PM, but
this is a clear example of a choice that, only for saving few dollars now, can
take on a big money loss in the near future.
I don't know if I'm updated with the current pricing, but (only in order to
understand the problem) these are real facts:
The XP Professional License costs around 299$, while Windows Server 2003
costs from around 1000$ and above. The company's PM wants to
reduce the costs, so he decides to choose Windows XP Professional to
host the company's portal.
I don't want to consider now all the security advantages that Windows Server
2003 has, but here there's a main aspect to consider, that the PM maybe doesn't
know: XP Professional has a connection limit!! It allows only one root
website, and a maximum of 10 concurrent connections to that
website (this limit is installed by default in the metabase key
MaxConnections for W3SVC).
Obviously, there are tricks to change these limitations, but you can't do
miracles:
- You can run only one root website (for example http://myPortal), so if your website runs under a
subfolder (for example http://localhost/MyPortal) it's all ok, otherwise
you can use this
tool that can permit you to solve this limitation (not completely, because
only one website can be active at any given time).
- To increase the connection limit (for example to 40, above is not
recommended), you can execute this script: C:\Inetpub\AdminScripts\adsutil set w3svc/MaxConnections
40
So, the company has actually spent 299$ for the XP Pro license and now has
all these problems to solve. Do you think that the PM will work here for a long
time again or not? 
If you think that the answer could be yes, now permit me another
consideration: Windows Server 2003 family is composed of different product
editions and one of that is called "Windows Server 2003 Web
Edition". The Web Edition is the ideal solution if you have hosting
needs, doesn't have any of the limitations above and its license actually costs
around 399$. 100$ more today but lots of less problems in the future...
This is a clear example of a bad choice. The PM now has not a long life I
think 
(but I hope that it's in time to read this post and take the right
decision again).