Microsoft has just placed an icon on my taskbar inviting me to sign up for my free copy of Windows 10 when it becomes available. Ordinarily I would go for it (upgrades must be better, right?), but given the complaints levelled at Microsoft's last OS I'm not so sure. I currently have Windows 7 which I'm very happy with, and I'm reluctant to risk spoiling my experience. Do any of you with more computing expertise than myself think that Windows 10 looks likely to be worth it?