CRM middleware and SAP-XI ?

Hi Guys,

I need to integrate CRM with XI and CRM itself has CRM middleware. I am confused between the inbuilt CRM middleware and XI.

Is the CRM middleware still exists with the latest version of CRM ? When i should go for XI?

What are the adapters do i need to use to exchange the data with the CRM ?

Do i need to convert Bdocs in CRM to Idoc format before sending to XI?

any help would be really appreciated

Thanks,

srini