I had some slow issues with Virtual Box, which I've heard have been fixed. I'm heading back down the VMWare path and did some research first.
I found this post and tried it out. It worked great. My VMs are moving at my required speed now. The latest version of VMWare 1.06 still requires some bash shell work. This post gets you setup good.
I'm running Virtual Studio 2008, Re# 4.0 (latest nightly build), and a couple other apps.
Using virtual machines have become the development de facto. I'm finally getting back into the grove with ASP.NET MVC and some ExtJS stuff at work. (THANK GOD). We've brought in the latest Rhino Mocks (3.5) and Castle Windsor. Fun stuff ahead.