Slow with every new update only means the software is becoming more demanding. I have an old IBM PCServer 330 that's incredibly reliable - if it were not for me rebooting it every few weeks to make sure it brushes its teeth regularly, its uptime would be in the multi-year range. With two Pentium III processors, it's anything but fast, but it's as trustworthy as servers can be.

I'll eventually have to replace the hard disks - I have seen SCSI to CF and SCSI to SDCard adapters that may do the trick.