|Can vista span/merge harddrives without loosing all data if one drive fails? (using a recovery tool is ok)|
You are limited to a few choices. Raid is the normal solution for speed and security but you do need more than one disk and normally a well built controller for hardware raid.Many are either software or so called "soft" raid controllers. A true hardware raid controller is fast and reliable.
Second is a backup solution. Vista has a way to make images that can be restored with the bootable vista DVD.
There are plenty of other backup and image solutions too.
"Best Practices", Event viewer, host file, perfmon, antivirus, anti-spyware, Live CD's, backups, are in my top 10