help creating a calorie goal

I everyone, MFP's net calorie system really gets me confused sometimes...butI don't want to switch to sparkpeople because the database here is better. I am just looking for some opinions. I have about 40 pounds to lose. I currently MANUALLY set my net cals to 1700 and just don't add my exercise to avoid confusion. I eat mostly vegetarian with the occasional lean meats and or fish. I also eat low fat dairy and eggs to help with protein needs. Here are my stats:
age-30
weight-185
height-5'7
athletic muscular frame (previously an athlete)
goal weight-150

my question is: is this a good calorie goal for me to have? I am guessing if I eat 1700 and work out moderately I will be "netting" low enough to lose??
Thanks so much!:)