Vista is definitely much more secure than legacy windows. It’s not affected by common viruses and Trojans. Its interface is also slightly better, but it’s too heavy on system.
Mac & Linux can provide better graphics without much load on system. May be Microsoft over estimated the hardware capabilities of today’s PCs. Instead of designing good code they relied on power of hardware. Although people around the world use very powerful machines (with lots of Giga’s in CPU, RAM & HD), but Vista demands too much.
One very good feature of vista is very long battery life for stand by mode. If you put your machine running vista on sleep (stand by) mode, it consumes very less battery and on average can go for 3 days. Some people have reported up to 7 days of standby time. While Windows XP on same machine will give standby time in ‘hours’. It’s really a feat to change the battery consumption by changing the software only. I
don’t know if XP SP3 can achieve the same in stand by time. Apart from this there is nothing much in vista. As now SP3 is launched for XP, its security level should equal vista. So now there is no reason to use vista.