What is it worth?

monitor maybe up to $100. but i would not spend any money at all buying it because it will probably be of no use except maybe word processing and surfing the net.

If it has a valid copy of Windows XP (probably only has Windows 98SE at best) and you can get 25-character product key, I would start to consider purchasing it for word processing, email and surfing...but it is really on the edge.

I still get use out of a Gateway P3 500MHz, 384MB RAM (upgraded from 128MB), 120GB HD (replaced slow, loud 20GB model). It dual boots Windows XP (started with Windows 9 and the Linux flavor of the month.

If it already has XP:
You will want to upgrade the memory to at least 256MB, but you be happier with more. Many of those machines take type PC100 and/or PC133 memory for a maximum of 384MB. You would be lucky if it takes 512MB. It'll cost you about $20 per 128MB memory module, so your bottom line may be about $100. You may also need a mouse and a larger HD. Its old HD will be slow and loud.