For those who want to boot Windows faster, I highly doubt they will see a difference.
I know I did... I went from a 320GB Hitachi, which took roughly a minute on my old q6600 rig. I switched it to a raid 0 of 750gb seagates for a while, maybe 40 seconds was the best I saw. I put in a Vertex 2 50gb and it was from post to loaded in just over 20 seconds. The current system I'm running has 2 vertex le 120gb drives in raid 0 and it goes from post to loaded in between 15 seconds and 25 seconds (depends how long the ASUS bios takes to "locate" the ssd array during post).
I did notice someone mention rebooting the system and using sleep. I used to sleep my old system on the mechanical drives because of simplicity of coming back up to a running system. With the SSD though, I could just shut down all the same and be back up and running in a little bit more time then sleeping. I used to leave my system up 24/7 though, and it did do around 8-9 months on win7 without any updates installed and no shutdowns. With my new system, I shut down every time I get off, as 15-25 seconds from pressing the power button to running is enough for me to justify no power wasted when I'm not using it. (This has more to do with running a server using around 200-300w average on 12 drives, so having another computer pulling 250w idle wasnt something i wanted to add to my electric bill)
I like SSDs, I love space of mechanical though. I use an SSD in my desktop and my laptop, and I plan to make the system drive of my server an SSD as well (mainly because when I replace the Vertex LE drives, I'll have 2 spare drives). But in all honesty, it does depend on usage. If I leave my system running all day with the same apps open, no need to really read the drive much, it doesnt have much benefit. When I'm starting the system, loading apps for the first time, loading maps for games, it makes a huge difference. Given, that isnt to say the extra 10-20 seconds to load a map will be the end of the world ... but we do live in a "I want it now" world, and most of us do want it to go as quickly as possible.
On a side note, my laptops battery life went from roughly 2 hours to around 3 going from the 7200rpm drive it came with to the ssd. Older ASUS ROG laptop that had a 500gb 7200rpm installed in it.