I've noticed that things have changed a lot now that I'm not a student. The biggest difference is that instead of having all time and no money, I've got no time and some money. This has changed the way I look at things.
I used to like to tinker with software. I've spent years trying to get things like OpenBSD firewalls running and fitting Debian onto a 200MB hard drive so I could turn a spare P90 into a webcam/apache server. My reasoning behind this was that I really did have the time to dick around with it and that I was learning a lot in the process. Looking back, I think it was a worthwhile way to spend my time.
My perspective has changed in that the list of things that I'd like to do has been growing very quickly and the amount of time outside work to do them in has shrunk considerably. And the thing is, mucking with a Linux install is pretty low on the list of things I'd like to do at any given time.
So here's a quick list of the reasons why I think IIS will save me time in the long run:
- It's trivial to install. I've done a handful of Server 2k3 installations at the office (primarily because working at the DLL level means I hose operating systems pretty easily). I've seen a few Linux installs get close (SuSe, etc.) but in the end, they're crippled by things like driver support.
- It's really pretty simple to change configurations. The biggest problem that I've run into with my Linux file/webserver is that changing something that I haven't changed before has inevitable rampup—sometimes serious rampup. And although it's nice to spend an hour learning even more about system internals, it's my hour (not my boss's, for example) and I'd rather spend it elsewhere.
- The maintenance system is more mature. I have watched every apt-get upgrade on every Debian box I've ever run. Stuff breaks when you apt-get upgrade it. Sometimes apt-get fails outright—but more often, stuff just quits working. As much as we'd all like to point out the handful of MS critical updates which have broken some software, I've never run into those issues (despite some four years of running Windows Update) and I've run into the apt-get ones pretty often.
- Did I mention the updates? Right, my point here is that I haven't found a Linux update system that's stable enough to, say, put in a cron job. And if these things aren't scheduled to run automatically, then a good deal of the benefit is lost.
Admittedly, there are a few things which make IIS really attractive to me, in specific. I don't expect most of these things will apply to most other people, but I'll list them so you've got an idea:
- I have no need to muck around in OS land any more than I do already. Really. I spend 8 hours a day in the bowels of the world's most widely-shipped operating system. I don't have a burning need to dick with config files or tinker with source code on my time off.
- Server 2003 (with IIS) is cheap. In this case, it's free—Layla got a free copy for something job-related. But even if it weren't free, it's cheap as an employee. And you know, even if it weren't cheap or free, it would probably still be worth getting it. I can't really put a price on my time anymore...mostly because my boss does put a price on my time, and it's enough that ... well, you get the point.
- I like "dogfooding" MS products. "Dogfooding" is a Microsoft term (I don't know if we invented the term, but we do use it a lot) ... err, term for running the software that you produce. I doubt that I'll be finding many (any?) issues with Server 2003 (it's a really solid product) but I like to give it a shot anyway.
So that's it, in a nutshell. Until the blog migration occurs (Movable Type works under IIS!) I'll be keeping the Linux server online—the biggest problem, actually, will be moving the database from MySQL to ... something else. And I figure that just for grins, I'll keep a copy of Debian (or something similar) running under Virtual Server—which, by the way, blows VMWare out of the water. Hot.

I wouldn't call 2k3 server "cheap". You're looking at $1k retail, or $400 retail for "Web server edition", which is a somewhat crippled copy of Server. "Web server edition" might be a good idea unless you plan on having more than 5 authenticated users.
IIS is probably a good idea for you, if for the "dogfood" reason if none other. I still think it's not viable for most home users, even with moderate-scale websites. For instance, for clanspum.net I would need a real copy of 2k3 ($1200 for 10 CALs), plus 40 more CALs ($1600). That wouldn't allow me to add any more users. So, for $2800 I could "upgrade" to IIS on my machine. $2800 is the amount I will pay for 28 months on the current server, including domains, IP addresses, and everything else.
Oh, and if I wanted X forwarding like services, that's $3000 per 20 users. Even if I keep access down to the people who currently use it (as opposed to the people to whom it is available), that's $5800 to "upgrade". That's almost 5 years of service with the current machine.
I'm getting my prices from the Microsoft Windows 2003 Server Pricing page.
As for updating, I have found Gentoo's updates to be as reliable as Windows updates have been in the year previous. It has managed to always warn me when it might mess things up. They also require substantially fewer reboots than the equivalent Windows updates. While I am not running the updater in a cron job (because I'm a control freak), I know people who do, and their experience is similar to mine.
I think that most of your arguments come down to which you are more familiar with. You spend a lot of time messing with Windows Server boxes, so you can set it up fast. I spend most of my server time on a Gentoo box, so I can do that fast. Configuration, likewise.
Agreed on the price. If you're in the business of supporting a lot of users, then going the commercial route may not always be the best idea—the number of people and operations you support is much more akin to a small (medium, even) business than a personal setup. Microsoft's pricing plan is geared to this, and I don't think the numbers you've outlined are that unreasonable for a business of that size.
Actualy, the first time I ever touched Server 2003 was about two weeks ago when I started using it en lieu of my XP installations. I'm much more comfortable with Linux config—at least, getting them started.
You use MySQL, you like hotmail, you think Debian is harder than Windows. You twisted, twisted person.
Anything can be conquered with enough time. Debian takes more time to deal with than Windows. Ergo, it's harder.
And yeah, I'd like to get away from MySQL. The install process for the all the ported-from-UNIX-land apps has been a giant headache.