Upgrading problems

Hi,

I am running multiple websites using WordPress. Two of these were/are still running on WordPress 2.6.3, but since other websites of mine are running 2.7.x and I’ve tasted the sweetness of these newer WordPress installs I want to upgrade.

I tried upgrading website #1 using the upgrade guide on this website, luckily also following the backup step quite precisely. I ended up breaking the website. The upgrade process failed miserably – and I tried many times.

My other website running the old 2.6.3 version is rather important to me. I therefore do not wish to break it. I do not wish to risk to break it.

I was wondering if there is another way of getting the newest version online? I was thinking about removing the old install completely, excluding database, and uploading the new version.

Would this work? How would I go about getting my old articles up and running? I rank quite highly with a number of them in Google. Do I risk my rankings?

In short: The upgrade process has failed me numerous times, for reasons unknown. With this website I can’t risk losing/breaking it. How do I go about getting the newer version without risk?

ps: the other website was never fixed, reuploading the backups still gave a broken website. It’s scary.