I had the impression that it was more stable using Windows' Remote Desktop feature compared to VNC. Here's a tutorial on how to use it:
http://nerds-central.blogspot.com/20...fast-qemu.html
By the way, perhaps the commands did not work because you have to run them as "root"? Specifically, I was talking about
:
qemu -hda image.qcow2 -hdb /dev/sda1
This works fine for me.