9780 BB T-mobil in Italy
 

I have a 9780 BB with T-mobile and am going to Europe for 3 weeks. I will be in London, Paris, Switzerland and Spain but mostly in Italy.

I use my phone extensively for business while traveling and always sign up for the international plan for my e-mails and have no problem getting my e-mails pushed while anywhere in Europe. I would like to know if I could get a card to slip in to make phone calls when I need to at a cheaper rate or if I do get an win sim card or something like that will I still get my e-mails pushed to me. ???

I am very confused as to how this works and what the best thing to do is here. I am mainly interested in Italy as I will be there most of my time but do travel to Europe to different countries from a few times a year.

You should be aware that once a Blackberry is registered for Blackberry Internet Service with a certain operator you can not activate BIS with another operator. So if you have activated BIS with T-Mobile USA your device is tied to them and you won't be able to get BIS for your device with any other operator in the world even when swapping SIM cards.
We discussed this issue in detail here.
You can use another SIM card in your Blackberry and use it for calling, but you cannot get BIS on it with another SIM card unless you cancel BIS with T-Mobile USA.