Does USB work for you?
I couldn't get it working last time I tried - Win7x64 host, XP guest.
Yes, USB works for me...It didn't work for me as well at first. I found that it wouldn't work on usb ports on a pci usb card. Only works on your motherboard's usb ports. I have exactly the same set up as you.
If I remember correctly, I just plugged it in when my guest os booted up and then right click the usb connection icon on your virtual machine window and select the appropriate usb device. If that doesn;t work, you might have to connect the usb device so that your Windows 7 detects it and select the filter for that device on your virtual machine's usb settings in Virtualbox.

, It is also very very good but I wouldn't take the number of users as an indication of its quality compared to VMWare. Personally I use VMWare but having played around with all of them they are all very good. It really just hinges on whether or not any of them offer a feature you need which the others dont.