Just registered to say a big thanks to y4mz, roseway and waz101 for their help above.
Just got my 'new' DG834GT from ebay this morning, and by lunchtime had successfully bricked it. (I got the 'magic hardware header could not be found' warning when flashing with nftp from the DGTeam site.)
After recompiling nftp with the code above, I resurrected the router. I'm not that great with Linux, but it saves my skin time after time...
Just wish that the Netgear recovery utility would work with Windows 7, it would make things easier.
Great community here, I've been lurking for quite a while.