Is there a significant difference between a solid state hard drive and a regular one?

For people who have used computers with both, have you noticed a difference in performance and speed? How much of a difference? How significant?

As I’ve indicated before, I am planning on getting a PC laptop to go alongside my Mac (as soon as I sell my old PC laptop). I want to get one with a solid state drive, but they are hard to find. Really only the HP Pavilion and the Dell Studio XPS were the ones I could find with solid state drives.

I was really motivated to get an SSD after my Mac’s regular hard drive crashed. I heard SSDs don’t fail as often.

So what’s the deal with SSDs?