Does anyone know of any alternative to the Nanacom? Does any company make an interface and program that would enable me to diagnose and reset the "ECU" on my 2004 Discovery TD5? After all I have quite a mass of computer power; old desktop, old laptop, new notebook, new phone and new tablet.

only reliable alternatives with programming capabilities are Lynx(which is an interface), or Hawkeye(handheld tool)... though both close to Nanocom price range, you'll not find any cheaper thing to be able to properly program a Td5 ECU whatsoever, only more expensive...and that's certain

though if you only want to read and clear fault codes seach for "Autocom CDP pro"(or similar) but this is very limited with no programming capabilities