What Considerations For Buying Used Motherboard?

I have an opportunity to get a couple of used motherboards for $10. They are an

Asus P5E VM DO
and an
Asus P5QL-CM

The first one is from a system that is no longer working, but the faulty part is not known. The second one is probably working according to the seller, but he's generally pretty unsure of what he's got. He may or may not be able to find the manuals.

I have never built a computer before but want to build a budget system. These mobos are are being thrown in by the seller from whom I can buy a case and power supply from which I can use anyway (Antec 900 case and Antec Earthworks EA-650 power supply)

Some of my questions are:

- Does it seem like a good idea to even see if these mobos will work? (Might I make more trouble for myself than it's worth, etc.?)
- Is there any easy way to quickly tell if the mobos are working or not?
- Will I be able to download manuals for them from Asus's website?
- Are there any miscellaneous parts I should be getting with them? What would those be? (Seller said he would throw in the miscellaneous parts, but seemed unsure of what they were or what he still had or could find.)
- I think these are Socket 775 mobos. If I buy a Core Duo cpu and plug it in, am I risking any damage to the cpu, or is the worst that can happen that I just have to buy a new mobo and can swap the cpu over?

PS: He has a Core Duo cpu I could probably get for a few dollars more also. I'm not sure which one it is. Should I buy that also if it's real cheap? What's the most likely thing that's broken? The cpu, the board, or the ram? (Somehow I am assuming it's not the power supply, as I was counting on that being good.)

PPS: I am getting the case and power supply for $80. The two boards for $10 more. Maybe if I could get the cpu and 2G of ram for another $20 or so, should I take it? Then I would just have to figure out what the bad part is, and I could hopefully build with the rest. I don't know much about troubleshooting something like this though. Also I wanted at least 4G of Ram, so I didn't know if his 2G would do me any good.

It might be more of a hastle to get unknown parts then to buy new reliable parts. I bought an old camaro to fix up to learn about cars and auto body, but it has given me more problems then i can handle so instead of being a learning experiance it's more of a waste of money at this point.

However, you'll learn a lot more i think if you have to diagnose and fix an old computer. If i hadn't gotten that camaro then i wouldn't have learned what i did. You just have to judge if it's going to be worth the time and effort.