[McMurdo]

You can buy purpose made converters that will accept composite video and convert it to VGA for a modern PC lcd or crt monitor...expect to pay £40 upwards.

The proviso is that you'll need to do a little mod to provide your spectrum with composite video out...it comes as standard with only RF. Various computer forums will show you how to modify the spectrum for composite video, this is a popular mod as the original RF (TV) output from the spectrum is poor. You will need to remove the circuit board from the spectrum and do a bit of soldering.