It will depend a little on what else is in your system, but without a SSD it took about 1 min 2 seconds to boot, on an SSD about 25 seconds - plus, you click on web-browser/programs etc. and you don't have to wait for them to load at all! I could use any number of examples, but I don't run a high end machine and the change was vast
Much of the slowness associated with too little RAM can be solved by a SSD - I'm able to run games such as GTA IV and Max Payne 3 on Medium settings with it which would have lagged a lot before.
If you have 3 to 6GB Ram and a HDD, upgrade to a SSD before changing the RAM
I was astonished at what I got in terms of speed boost the first time, I must admit.
@sHn33Ky - I too like sony, a sight word of warning though, although a laptop is great for portability, I prefer a desktop so its easier to upgrade. Many laptops are far more limited in terms of what you can change (Look at the mbp, they even vacuum seal those now...). Thats possibly me and personal preference though, I like to mix and match bits of hardware.. :p