Although I have the latest systems (PS3, windows based machines, etc) I like working with the old system I grew up with in the 80's such as the Commodore 64, Atari 2600, Apple IIe, Amiga 500, Atari ST, etc. I look for these items at yard sales, on ebay, etc. and hope to pick up some of them soon. Most of all because of space limits I want to be able to share the same monitor with most of them and have a spare lcd monitor that has both vga and dvi connectors.
My question, most of these machines have rf or at least a rf option. Some have composite. Is there any way to convert rf especially and maybe even composite to vga so I can simply hook it into this monitor as well as have the audio connectors for external speakers? Is there some type of switchbox that does this?
If this is not possible my other option would be to convert rf to composite or s-video to display on my dlp tv.

http://www.viewsonic.com/support/accessories/tvvideoprocessors/nextvisionn4/

Or similar devices. I used the N4 for awhile, but it only supports 1024 x 768 even for the VGA pass through. The N5 and N6 should allow for the 1280x1024 on the VGA pass through. Since your monitor already has two inputs use the DVI for PC and the VGA for this. A simple AV switch in addition to the N4 should allow you to connect as many devices as you want.