I've got a new business name and a new website. Go to www.smilodoncreative.com to learn all about it! 

Ask a Nerd: How long will my new artist website retain its shiny, healthy glow?

You launched! Your website is perfect and has a bunch of fresh blog entries/work samples/head shots/whatever.  Now you can kick back and relax for at least five years, right?
Wah-wah. Hate to be the bearer of bad news, but to put it simply: No. You can't.
I'm not even talking about creating new content for your website.  I'm talking about making sure your website keeps running. Modern websites need regular tune-ups and occasionally they need serious work. Sometimes you realize you really need a new function.  And, sadly, at some point, websites have to be replaced. 
The days of super simple websites are, mostly, gone.  I mean, if you want five pages that don't do anything dynamic, you can have that.  But if you want a website that intelligently displays relevant content or that doesn't require massive amounts of time to update, you are going to need something a bit more complex, like Drupal or WordPress. 

1) Longevity.

Your website is not going to last five years.  If it does, the last year or two will be painful as you become increasingly afraid of making changes and the site becomes less and less predictable.  Your website is going to last 2-3 years.  Budget and plan accordingly.  

2) Maintenance.

Your website is going to need regular maintenance (think once a month or so). Both Drupal and WordPress are complex enough that we discover security flaws as we go along, despite everyone's best efforts to keep them secure. When one of these security flaws is fixed, it means every site needs to be updated to include the new fix. Sometimes those updates are simple, but sometimes they aren't. 

3) Backups.  

You can't backup your car (unless you're talking about getting down my very long and narrow driveway).  It would be great if you could just restore your backup when you accidentally hit a curb and blow out a tire, but you can't. Thankfully, with a website you can do just that.  Installed an unfriendly plugin and now you can't get to your content? Just restore your latest backup. This means you do need to <i>have</i> backups, so make sure you've got a plan.

4) Improvements.  

As my clients use their new sites, they inevitably find a few tweaks that would make their lives a lot easier.  This is the kind of thing no one can predict. Leave a little bit of your budget for after the project so you can afford these tweaks.  Maybe you decide you really need a houndstooth background. Maybe you want to add a picture next to your byline. 
Like I said before, sorry to be a bummer. But a website is a living entity and it's worth the time to make sure it's healthy.  When I work with someone, I try to be clear about what they can take care of themselves and what they need to call me about.
p.s. Check out Sarah Von Bargen's list of ways to keep your WordPress website happy.  Maybe I'll do the same for a Drupal site one of these days.