Another el cheapo method (and 1 that I used for a while) was to plug a 2nd monitor into my Windows box and then plug my a1200 into the tv tuner card of that machine and output the to the 2nd display.
Could be used in tandem with one of the aforementioned adaptors (or composite), and image quality tuned further through tv tuner software.
Additionally I had the 2nd input of my monitor connected through a rgb to vga adaptor for productivity and similar screenmodes and just pressed the monitor input button to switch between 15khz/composite and 31khz/vga (although if Id had a rbg to s-video adaptor Id probably have just used that full time).
Not really better or worse than Cammy's suggestion, but just another way to make the most of what a person has and/or limit extra expenses.
