Bill Thompson, of the BBC’s ‘Go Digital’ programme, sets out very clearly (‘Sign software on the digital line’) many of the issues involved with ‘trusted computing’ and forcing the use of signed software.

“They want to use digital rights management to control what we can do with content we have purchased, they want to make sure we don’t install programs or new hardware that they haven’t approved, and they want to be able to monitor our use of the expensive computers we own.
This has to change. The focus must be on us trusting them not to take away our rights under copyright law or our ability to do what we want with our property. It should be about users being reassured that personal information is not being squirreled away and hidden software isn’t being installed.
I have a very nice car, and I try to take good care of it. It runs on petrol, but I want the freedom to fill it up with diesel and destroy the engine. It’s my engine, after all.*
The same goes for my computer. I want the freedom to write, compile and run my own code, take risks with dodgy software I’ve downloaded from the net and even break the law and risk prosecution by playing unlicensed music or running cracked software.
Partly this is because I value my freedom, but surely it makes me a better person if I have the choice and exercise it responsibly, whether I’m driving or surfing the web?

*Indeed, to take the car analogy a bit further (and I know this is overdone in online debate!), I want the freedom to fit an aftermarket induction kit, or stainless exhaust, or a proper spare wheel, without the car phoning home to the manufacturer and locking up the ignition. I accept that some modifications will invalidate the warranty, but that’s different to deactivating the ECU remotely and permanently, which seems to be entirely possible with some proposed ‘trusted’ computing/’technical protection measures’.