VMs run all of them crazy easily. And using unity you can have all versions on your desktop at once and open. I do it every day. My default browser is IE 9,

VMs run all of them crazy easily. And using unity you can have all versions on your desktop at once and open. I do it every day. My default browser is IE 9, so when i launch I always launch in IE 9 do all of my testing debugging there, almost never even look at another browser until it works 100% there. Then my browser for surfing is Opera, all others for testing.