Assemblies are supposed to be language independend so a .net assembly (.dll) written in c# is useable with delphi prism at once.

The commandline editions of delphi prism can be downloaded for free here:
https://downloads.embarcadero.com/free/delphi_prism

And here is howto use XNA with delphi prism aka chrome:
http://chrome.pascalgamedevelopment.com/