The PC does do some work. It acts as a backup for my laptop and music collection. However, I don't NEED it for that. That's just a fringe benefit. Likewise, I do my photo editing on it, but I could run Ubuntu in a virtual machine on a big monitor and achieve the same end.
If I rebuild the PC, I have lots of salvage. I could keep the power supply and case, keyboard, and monitor. A new motherboard + memory + CPU combo would be around $300. I'd have to keep the power requirements down, so I've have to pick a dual core, or otherwise redo the wattage. I'm sure that I left wiggle room, I just don't know how much.