Planning to buy Lenovo Z61t, need some info!

Hi all,
these days I am planning to buy a Lenovo Z61p laptop with the T7200 processor (2GHz). I need answers for the following questions, because I can't seem to find answers on the net. Here they are:

How much does the computer work on battery with the 4-cell one? (and it is set to "Max Battery" mode in windows )
How much does the computer work with the 7-cell one? (again "Max Battery")
I saw on the net, that it has an option to install a second battery via the Ultra Bay. How much does this bay cost (approximately of course) and how is it installed on the computer?

Thanks for all the information you can give me.

 

you mean z61t, right? (you have z61t in your title, but p in your thread)

i have a 7 cell battery and a z61t, and i get about 4 hours out of vista with max battery settings (it was about 4.5-5 hours with xp). Sometimes more, sometimes less, depending on the amount of internet usage.

for info on the ultra bay battery's pricing, check the lenovo website. from my knowledge, it replaces your cd rom drive in that slot on the right.

 

Around $100 from newegg for the Ultrabay battery.

http://www.newegg.com/Product/Product.aspx?Item=N82E16834995034