Determine OS and web server software

[Joel Hammer]

I used to know this, but...

What is the trick(s) to determine which OS and which web server software
a web server is running?

I just came across a bothersome problem. I wget'ed -r a web site to a
linux box and all went well. However, when I copied this site over to
my USB flash card (which likely is preformatted in vfat or some such)
I had a collision of two directories, which were spelled the same but
had different capitalizations. So, I guess the web server was running
linux/unix. But, I would like some way to tell this more certainty.

Is there some easy trick to overcome this problem? It won't be hard to
fix this one problem, but, this could get tricky if there were a lot
of collisions.

I also want to get some data on which OS/software they run. I may
need some data to do some convincing of our IS dept, which is an MS
monoculture.

Thanks,

Joel