i came to realize it's a cult issue, Linux vs Windows "debate" will never end, just, few points to make things clear and fast.
use Windows Server 2003 if you want the following:
1. Ease of use (compared to Linux) specially if you are upgrading from XP or 2000.
2. Compatibility, just name it! 90% of the apps out there run under windows.
3. Microsoft products integration, who are we fooling? MS office is the most powerful software suit and it's getting better with each new release! and now with the Dot Net framework integration with office 2007, nothing can stop them mofos.
4. MONEY.. yes, MS costs alot of money when it comes to buying "original" licensed sofware, but what you'll get from this software is worth every penny you put, specially when it comes to the experince.
5. for web programmers, full asp dot net support ofcourse, and ASP dot net is much faster than PHP
even though i love PHP, ofcourse you can host an ASP site on a Linux box, but it'll never perform like it performs on a windows box, NEVER, it'll peform as slow as a heavy bad written code from the early 90s
ok now use Linux for:
1. gain solid experince in programming/scripting, as most linux dsitros provide "out of the box" tools to write a code.
2. security - because with linux you can nearly modify/rewrite anything since it's an open source OS.
3. stability - the reason is the same for 2 plus linux utlizes the resources better than Windows (from my experince).
4. MONEY .. it costs nothing download it and deploy it...
that's all ofcourse we are heading to an OS-Independandt IT world, where you can do whatever you want whever you want, but still, i'd pick windows over linux for any RAD company..