Got to be honest, I'm not too sure why so many folks get so hung up about "improved" boot time with SSD's? There are so many other factors that effect this.
EG. what apps you have kicked off at start up (AV's being the single biggest culprit for slowing start up times), even what mobo / BIOS has an impact (some are just slow to boot). Can't say that I notice a great difference between my Vertex 2E and my Velociraptor to be totally honest. certainly not enough to start waving my willy about (so to speak).
Though applications that run entirely (IE. including files that they access) on the SSD are certainly pretty nippy. Though I don't thing it's quite as life changing as some make out. Depends on what sort of drive set up you come from I suppose. And as most will be coming from an older established system to a new install of Windows, I think you just sort of forget how much quicker things seem on a pristine system. Only my opinion of course.
The nice thing about SSD's is it doesn't really matter how many apps are kicking off, there's not too much difference between a 15s SSD boot and a 30second clean boot from a spinnie, but in my experience you can take a cluttered up spinnie install that takes a good 5 minutes to be usable, clone it onto an SSD and it'll be booting to usable in 20 seconds.
It's the multitasking capabilities of SSD's that make them shine, you can be doing a disk intensive operation like a virus scan or file copy going on and not even notice it in your other apps.
I've got SSD's in three of my computers now, can't stand using spinnie installs when I have to fix a relatives computer. Once they get a bit cheaper I'll probably start gifting them
I'd do an SSD upgrade over a CPU upgrade pretty much every time. It's removing a bottleneck.