Getting back into this late, having spent the weekend chasing gasoline chainsaws on poles, I would like to point out that anyone using a PC older than a pentium has got to have the basic skills of replacing the back up battery and working with analog to digital converters for interface or building such an animal ($200-400). Then programming in a wonderful old version of C or assembly language or working in Linux/Unix. As it happens, I have been involved in microcomputers since my January 1975 issue of Popular Electronics arrived and have worked with single board computers and assembly language and various PC's (personal computers, not just IBM PC where IBM stole the initials) for years. But the delights of putting tens of hours into programming and into accurate analog interfaces to be cheap have continued to escape me. Of course, so have the delights of being an interior decorator programming Windows (still using QBasic under the DOS window in WinXP for utility stuff, very stable unlike Win98) The amazing choices available in the fractional DIN format (2x2x4") for about $200 with another $50 or so for thermocouple and SSR and $40 for a UPS along with the computer interface that allows writing a high level monitoring program make the effort of a PC just a hobby. More importantly, all of this is nonsense if one is talking about controlling gas, where interfacing with the gas and air flow with proper safety features quickly drives the basic cost up close to $1,000 just in parts. And most potters use gas or oil because it is easy to heat a large space with a packaged solution that heats and shuts off using cones that take in the heating rate - longer for a slow rate, etc.