Guys i need some help with a decision.

I will definitely buy the n900 the moment it comes out. Now here is my scenario:

1. I am currently on at&t without a contract.
2. I am ready to switch to t-mobile. Now my dilemma is wether to take a contract or just take a regular voice + data plan without a contract.

Consider the first scenario: Contract for 24 months.

I can go to amazon and buy a htc touch pro 2 for 150$ and sign a 2 year contract. I have 150$ worth of gift cards for amazon. Then i can sell the touch pro 2 for about 425-450 on ebay and use that money to buy the n900 with the remainder coming from selling of both the n95-8gb and n810. In such a case the plan would be 40$ for the voice and 25$ for unlimited internet.

2. I could not sign a contract and just buy the n900 with my gift card + n810+ n95-8gb+ any additional money if needed. I can call t-mobile and tell them that i have one of thier other phones for which the internet data price is 20$/month + regular 40$ voice plan. What this gives me is 5$/month cheaper plan and the ability to not sign a contract. The only problem is that i do not know if i can call them and take that plan

This is the plan i am talking about:

http://www.t-mobile.com/shop/addons/....mc_t=OnsiteAd

SO guys tell me what would be the best way?

Thanks