I have a dilema, I would like to buy a 8900 Curve from tmobile however they do not offer a data plan on pay as you go services however various other networks such as o2 offer payasyougo email data plans, so what i would like to know is whether or not i could buy a data plan with o2 for my 8900 and use my tmobile sim instead or does the data come straight from the sim card?

Firstly O2 do not offer data plans for Blackberry on PAYG.
They offer it (like t-mobile) on SIM Only Plans (a 30 day rolling contract).
Orange are the only ones that offer PAYG blackberry data plans in the UK.(I assume this is where you are).
Secondly, no you cant.
The data plan is attached to the SIM.
You cannot get a data plan from one provider and use it on another.

T mobile currently have the blackberry pearl on offer....it offers unlimited email and unlimited internet for a year on pay as u go

carphonewarehouse.com/mobiles/choose-tariff/BLACKBERRY-8110-PEARL/PPAY/NEW

So would i be able to use the right to access email and internet on that sim in another blackberry i have such as the curve 8900 or does the email and internet register to the actual phone rather than the sim maybe even both?

The data plan is attached to the SIM.
You can use the SIM in another BB.

Thanks thats exactly what i was looking for