I opened an $100,000 MT4 demo account with a 1:100 leverage. When I place a 1.0 or a .10 market order how much is that equal to in USD?
It’s not the leverage that matters, it’s the account type.
With a standard account 1 lot is a $100,000 position. Mini is $10,000 per lot, and micro is $1000 per lot.
Looking at this question from a couple of angles, with that much I would expect that it would be a standard account, so a market order with 1.0 is [B]one[/B] standard lot and would make a pip worth approx $10.00 each, and .10 is [B]one[/B] mini lot and would make them worth $1.00 each.
Leverage determines largely in the amount of your account balance they hold (margin required) while a trade is open. So I think at 100:1 for each 1.0 standard lot, they would hold $1000 each from your account balance, and for each .10 mini lot it would be $100.
Hope that helps 
Your right it is the leverage that matters but:
1 standard lot = 100,000 [B]units[/B]
If the base currency is USD then it is equal to $100k USD, but for example if GBP then 1 lot = ~$159k USD (or 100k pounds)
1 mini lot = 10,000 units
Cheers
Your right, it is 100k of the base currency. He asked what the answer was in USD, so I assumed he was trading a USD pair… I probably shouldn’t have.