Hello there:-)
I mentioned that a simple xna application seems to use 7 threads so I am wondering, what exactly they are doing. Well I could imagine, that the render process is placed in a separate thread since the native Direct3D9::Present method is a blocking one. (As far as I know) Well, but what are the other 5 additional threads for?

Dear Greetings
Samuel

I don't know.

A default Windows Game on my machine only creates two threads, though. Judging from the name displayed in the VS threads window, one of these appears to be some kind of thread pool event dispatcher used by the CLR.

Shawn Hargreaves:

I don't know.

!!!! The Shawn, but... you always know!?!?

Some drivers are multithreaded - could be that...

You might want to download process explorer http://technet.microsoft.com/en-us/sysinternals/bb896653.aspx - it will show you all the threads for an app that are running and while module they are running.

When you've done it - let us know the results.

If this was beta or hacking/fixes on the XNA Framework itself that would be necessary to know.  Otherwise, it isn't important what other threads are doing.  Or to think about it another way, what are you going to change about how you use and touch the XNA API if you know why the system needs 7 threads instead of 6 or 8?  Especially if you have no control over the behaviors in other threads you shouldn't worry or interfere.  With some complex API, knowing what the man behind the curtain is doing is often unnecessary and may drive you insane. :)