You should definitely take advantage of the program if it is available to you. Since you are already a student at your school, you have a leg up, and will finish the MBA a year earlier than others who start fresh. Remember - if you do the MBA after some work experience, you are going to have to make time to do it, it is going to cost more (everything will cost more in the future), your employer will most likely not be willing to pay for it, you will have other responsibilities. Work during the day, MBA at night - or minimally fitting MBA work in while you also have a day job. Would you be able to stop working for two years to pursue an MBA full-time? For most people the answer is no. Additionally, once you get out into the work force, it is much more difficult in general to go back to school whether full or part-time.

Lastly, everyone know the economy stinks right now. If you were to come out of school and look for a job now, it is going to be extremely difficult for new grads - they are going to be competing with all those who are unemployed who have lots more experience and are going to be willing to work for lower salaries than they’ve been getting in the past. Competition is going to be very high. If you have the opportunity to stay in school a while longer, get the advanced degree, you’ll come out ahead of your peers going straight to the job market and the extra year in school will give time for the economy to recover some.

Definitely go for starting the MBA in your senior year at your current school - there are no drawbacks.