Removing suspension from a bike I'm looking to do a bit of light touring and want to outfit an old mountain bike to be up to the task. But most of the bikes I'm looking at have some crappy/mid-range suspension on them, which – to my understanding – only adds weight and an additional point of failure (at least from the perspective of touring).

What I'm wondering about is, is it possible to buy a fixed fork for a bike and replace the suspension? 

If so, what sort of things should I watch out for?
This should not be a problem. A decent Al-fork will easily replace a crappy 'suspension' fork. You'll just need to check for the right length and diameter of the stem and maybe replace the direction bearing as well.