Going to Paris for a month?

My girlfriend and I are going to Paris, France for one month I was wondering about how much USD I would have to bring for the hotels, transportion, and food. We already have the plane tickets. 
Thanks in advance.

1
US Dollars are useless in Paris. Bring Euros.

2
Don't bring cash. Visa and MasterCard are widely accepted, and you might also be able to use your ATM card in the machines here, to get money from your own bank account at home, you'd get it in the local currency Euros. But do contact your bank first and let them know where you are going and for how long. 

3
To find out the cost of accommodation, try www.hostelworld.com - but Paris is expensive. Food-wise, just go away from the main tourist drags, and go where the locals go. You could also get items from markets and cook your own meals, if you have a place with a kitchen. Transportation is handy, you could get a 'carnet', which is a little package of 10 tickets for the metro, or there are transport passes available for buses and metros.

4
You must give far more details - There are great extremes in Paris between highs and lows.
HOTELS: The lowest close around $100 a night and that would probably mean a room on the 5th floor in a building with no elevator (lift) - Fine hotels - will be over $350 a night - That would mean between $3000 and $10500 a month - Transportation - Do you mean just in and around Paris? If that is the case - the metro is not expensive and there are many ticket purchasing plans - Many taxis - and much free walking or taking the on and off sight seeiing buses or the Seine river tours. Really a guess but I think if you do not leave Paris maybe $30 a day or $750 for the month. Now if you plan to visit other places it can get expensive for two and depending on the day or hour many round trip tickets for two can cost you $500 - Food similar as hotels. Yes you can "eat" without spending much money - You can go to a bakery (boulangerie) and have light breakfast for two for $15 or at a better hotel close to $100 for two - Lunch and dinner same - you can find some cafeteria style or bistros and find good meals for two for about $30 or go to a market like Monoprix and find good takeout meals for about $14 of the two - Now the other extreme - if you are thinking
2 or three star well known places, you might be expecting got pay for the two $500 -$600 for a famous dinner