Thanks TM - I'm the only one around with any level of computer knowledge, so I don't feel the need for an encryption solution. I can keep the stand-alone secure without sophisticated encryption; it is the dialling-in aspect by outside software contractors that I am concerned about. I want to keep casual or intentional eyes out of the company business files, which are only on my machine. I am happy to go standalone for that, but I do need to use the LAN, too, on a routine basis - hence the question about common monitor, KB and mouse. My desk is cluttered enough without 2 sets of hardware!
And as you rightly point out, there are dangers associated with encryption and loss or corruption of the keys.