Firstly, you laptop is not doing a cold boot to the desktop in 10 seconds.
That is almost certainly coming out of sleep or hibernation or some other not-quite-off configuration.
Secondly...yes, an SSD is a good thing to have. And not just for reduced boot time.
Heat, vibration, power....all better with an SSD
Thirdly...a 120GB SSD is mostly not recommended. 250GB or larger.