Corporate owned laptops, should be using encrypted disks, etc, of course but you ask about personal computers.

I don't see this as a technical problem but rather a behavioural one. There is very little you can do from a technology viewpoint to make it impossible for someone to take code home and hack away at it - even if you can prevent them from checking out all the source to a project on a formal basis they can still take snippets home if they are are determined to do so and if one 10 line "snippet" of code (or any data) happens to be the bit that contains your secret sauce / valuable and confidential customer information / location of the holy grail then you're still potentially just as boned by losing those 10 lines as you would be by losing 10 pages.

So what does the business want to do? It's perfectly possible to say that people absolutely must not work on company business from non company computers and make it a "gross misconduct" dismissal offence for people who break that rule. Is that an appropriate response to someone who is the victim of a burglary? Would it go against the grain of your corporate culture? Does the company like it when people work from home in their own time and is therefore prepared to balance the risk of property loss against the perceived gains in productivity? Is the code that was lost used to control nuclear weapons or bank vaults or life saving equipment in hospitals and as such a security breach can't be countenanced under any circumstances? Do you have a legal or regulatory obligation with regards to the security of the code "at risk" because of this loss?

Those are some of the questions I think you need to be considering, but no-one here can actually answer them for you.