Laidbackfreak has given you a good answer regarding the amounts most EXPATS pay. As an expat, you will never get the prices quoted here by the Vietnamese posters, unless you live in the midst of a local Vietnamese "community", and the local police usually won't allow you to do that, even if you're married to a Vietnamese. (There are several other threads here on EB detailing that.)
The MOST you should pay for utilities, if it's just you and maybe a significant other, is what I pay every month:
Internet - 1,980,000 VND - about $96. (I choose to have the fastest ADSL connection I can get in my area because I cannot tolerate slow speeds. The slower connections here are similar to "dial-up" connections in the states.) My internet speed and bandwidth are very comparable to a good USA connection. Fiber-optic connections are also available in my area, but for MUCH higher monthly rates, and even I am not crazy enough to pay for that.
Electricity - on average, about 1,250,000 VND - $60. Mine is highest in April, maybe $75, and lowest in January, maybe $50. My AC is off during the day, and on all night.
Cable TV - $8. It's not that good - only a few English channels such as Discovery, NatGeo, CNN Asia, ESPN Asia, TLC, etc. But compared to the monthly cost of American cable TV, it's a bargain.
Water, Gas, etc. - on average, about $10 for both combined. Where I live, in the Q7/Phu My Hung area, the gas, water, and if applicable, management fees, are combined in one bill and paid at the community center. Management fees VARY WIDELY depending on the complex. If the complex has amenities such as a pool, exercise room, childrens' play area, well-lit, well-maintained common areas, etc. etc., and security guards watching every entrance 24/7, the fee can be as much as $65. Some complexes keep the fees lower by reducing security (and as a result, have a much higher theft rate) and allowing pay-as-you-go for the amenities.
So my total is 96+60+8+10+65= $239.
The key to all of this is to rent from a place that breaks all of this out, and allows you to pay it yourself, so you know exactly what you're paying for. Then all you have to do is negotiate your monthly rent with the landlord. If at all possible, do NOT enter into a situation where you pay everything, all inclusive, to the landlord every month.
Hope this helps.