There is a separate compatibility namespace, the DLL for which is only referenced if you've used the upgrade wizard however.
Using types in Microsoft.VisualBasic is not necessarily bad practice, but the types in there are not true .NET classes, in most senses of the word. They are only there as helpers for Visual Basic. There's nothing wrong with using them.
On the other hand, a common viewpoint (including mine) is that it's bad practice to use them, because when you inevitably have to write something in C#, or even read something, or convert something - you're going to be disadvantaged for having relied on those helpers in the past.
They can be very helpful for people struggling to make the transition from VB6 to .NET, but in my opinion the time comes when you don't need them to hold your hand any more, and you can use the pure framework like other .NET languages do.