old 20" cinema display a1038

You would need a video card in your PC that has a DVI output that supports 1680x1050, and this adapter:

http://store.apple.com/us/product/M8661LL/B

I have no idea what your second question means.

BTW, using punctuation helps make your post readable. It's really difficult to make sense out of a post that is one long rambling sentence.

Many of the most knowledgeable posters on these forums are not native speakers of English. Without complete sentences, proper grammar, capitalization, and punctuation, these folks cannot possibly understand your writing and cannot help you. Save text-speak for Instant messaging with your buddies.

The display you mentioned does not have a Power Supply of its own. The computer supplies nominal 28 Volts DC through the ADC connector to power it. To use it with a DVI-equipped computer, you would need the US$100 Apple DVI-> ADC converter, which has its own power cord and adds in the required DC power.

Dave has kindly provided a link to the only currently-available adapter that will solve this problem. The Belkin adapter cable is an ADC computer -> DVI Display adapter, and has no power supply. It will not solve this problem.

If your PC display card cannot do exactly 1680 by 1050 pixels, the picture will look awful.

I have a a 20" Cinema Display that's about four years old and would like to sell it. I'm trying to find out what it's worth. I went to Mac2sell.net but they don't cover displays and their value. Can anybody point me to a site where I can get an assessment of this displays current worth>

eBay; completed listings.