When you think of it, 8 years of uptime isn't special for a machine running on a UPS and not needing a reboot for software updates. There simply isn't a reason for a well-built operating system running on solid hardware to crash.
A software upgrade on the XP machines was ridiculous. It usually involved 3-4 hours of loading and booting and restarting with several different CDs. The other techs and I were convinced that NCR padded the installs/updates to take longer since their certified field techs billed out at around $300/hour.