Like Roberto, I too started with Apache. Then a friend told me about aD and so I started to surf their site. I found this little webserver called AOLServer, and my first thought was "It's AOL how good could it be?". Then I started reading Phil's book and talking with some other webmasters I know and I found out that AOLServer was pretty damn good! So I decided to download it and give it a try.
Well, installing and running AOLServer was easy, but I don't think it was any easier than Apache. Anyway, I spent a good three days trying to get ACS to run. I'm not an Oracle expert and I didn't want to spend 10K on their database so I decided to give ACS/pg a try before I gave up on ACS. It took me two hours to setup and configure this distribution of ACS thanks to the great documentation here at openacs.org . So far I love it. It seems quick. I am testing it on a dual celeron linux box with 256M ram. I don't have any concrete numbers, but it feels fast.
I can tell you this. I am going to decommission my Apache server and start using AOLServer with ACS/pg! The only downside is that the look of ACS is boring. I wish there was some easy way to make it look nicer. =) But its out-of-box features are great!
Gilbert