When you are doing a startup, your time is very limited and I believe you should go for anything that saves time & hassle without trading off much.
Btw if you are on Windows right now, you can still install and use Apache on it. There are differences but it'll be good enough for prototyping.
We have been using it on our servers and haven't had any problems.
As is the case, in my opinion with anything, just how you use it.
and to be fair less / no support may mean the product is so good that noone complains (it just works TM) or it's simply dead
on topic: contrast ubuntu and openbsd
I mean if you're considering Ubuntu, why not try the original? I use Debian as my main development box for exactly the kind of work that you're thinking of doing and I love it.
With Debian you will learn more about Linux than you will running either RH or Ubuntu. And if anyone thinks the Ubuntu repositories are great... They should also try Debian.
It has also had a reputation for being a harder distro to use... But I think this is nowhere near as true anymore as it used to be.
It's also worthy to note that along with the various BSDs, Debian is one of the most widely used operating systems for web servers. It's very stable and very good, due mainly to the excellent policy that Debian maintains in relation to how packages move through their experimental, unstable, testing and stable branches.
I will never use anything else as my main distro.
However, I'd choose Ubuntu (and have) for this reason, amongst others: you can run the same OS on your server as on your desktop. You might be able to do that with Fedora, too, but Fedora is not Redhat's main focus, like Ubuntu is with, well, Ubuntu.
Also... I'm biased: I've been using Debian since 1996, so it's what I know best.
I'm actually in a similar boat. I'll be building a dual-core box (intel barebones + cheap processor + 4 GB for <$300) to use as a dev machine in addition to my Mac.
[1] = VirtualBox doesn't support multiprocessors for hosts. You may want another solution, but I haven't investigated the free Linux virtualization market at all (I think VMWare has a free Linux server, but I have no idea of its features). Paravirtualization is another option for a Linux-on-Linux solution, but I think it's too complex for this.
fast install: ~5 mins default + ~5 mins untar my-essentials.tgz + ~5 mins mercurial sync ... my box is production ready (sans user database)
easy upgrade: untar the tgzs, kernel, sync /etc from newer OpenBSD
no automatic update: it makes default install uniform, when $hit happens, just order another colo server with default install, ftp my-essential and resync
package & port & source: complete freedom ... for contrast, try to build (then patch) vim from source in ubuntu (you can't)
now the 'bad' thing: few forums: but most questions are answerable from OpenBSD's FAQ, afterboot and man pages
less new driver: good luck installing bluetooth (can't)
older software: only firefox 2, no ff 3 in packages and snapshot port (ff3 site lists binaries for xp, osx, and .mar? source ... no idea how to compile .mar)
i use OpenBSD as server (colo) and desktop ... then vnc my mac mini for ff3+firebug (i don't bother with linux emulation, dual boot, vmware etc)
old simple vnc works across OS/arch ... i avoid fancy newer tech. Can you run i386-ubuntu and powerpc-tiger in one desktop?
i had enough of ubuntu, can't install from source, auto-update always break things (i finally quit after my ubuntu retarded to 800x640 and failed attempts at xorg.conf)
oh wait, did i mention about the quality of the OS by OpenSSH maker? Last time my colo lasted 4xx+ days without reboot
