Hi, I figured I'd chime in about my experiences with VirtualBox.
I've got Vinux, win XP, and Windows 2000 installed in VM's. I used NVDA to navigate the VBox interface, no need to use VBoxManage (the commandline utility) unless you want to clone disks, all the rest can be done with NVDA in the main VirtualBox GUI now, I'm glad to say.
I've got 4GB of RAM and an AMD Quad Core Phenom2 overclocked at 3.92 gHz, so I can run these all with no problems at the same time. I do eventually want to upgrade my RAM to 8GB.
I do agree somewhat with the sound issues. One of my Windows VM's has a really annoying stuttering effect and I need to play music in the background softly so that JFW can speak normally. Another thing is the slight lag between key press and response in the VM, about 300 Milliseconds. Not that big of a deal, but figured I'd mention it.
Other than that my experiences have been pretty positive.
SG