I run the WindowsXP virtual machine on Windows7 as well as VMWare, but not both at the same time. My preference between the two happens to be VMWare, but only because I tend to work from home and want to isolate my work traffic via VPN from my normal internet traffic. That is, I can establish a VPN connection to work and route traffic for my email, fileserver, softphone (voip) traffic to the VPN connection inside the virtual machine, while maintaining a separate internet connection on the physical machine - but still using the same network card. Since each machine (physical and virtual) has their own IP address, I can split the traffic, which I cannot do with Windows7 and the virtual XP that microsoft provides.
Other than that one key difference for me and the way I work, your observation of there being no noticeable difference in speed with Microsoft's virtual XP on Windows 7 is spot on.
I'm going to give VirtualBox another look-see, it's probably been too long since I have.
It's conceivable that Wave could make it possible for FR threads to be summarized into more coherent form. It could be a solution for the problem of the last poster - I prefer to hit the articles when they're first posted, rather than joining late into a conversation, because I tend to get involved in a long analysis of an issue - and if the thread is already old, by the time I actually hit "Post" people have moved on and nobody will ever notice my brilliant post at Reply #162.