shuffles,
most of the info I can fond on that issue are related to some type of corruption of the Outlook Express installation itself, and not something you can really be preventative about. The amount of mail should not be an issue, you are limited locally on your machine by hard disk space alone, and getting rid of mail would have nothing to do with this particular error.
The instructions you referenced are for trying to correct the issue, but have nothing to do with preventing it.
Best thing to do is make sure you have backups of your mail. If anything happens, you can uninstall Outlook Express, then reinstall it, and import your e-mail back into the new installation by way of those backups.
V