Speed is not the main thing, multitasking is!
You can load 10 things at once on the SSD and not slow to a crawl, which is why it's so great for an OS drive. Put your pagefile and Temp folder there, and it doesn't flinch.
It would take seriously over a minute when the Windows desktop showed on a boot due to the HD thrash of all the apps loading at once....
On the SSD it's down to 3-5 second - boom, everything loads up together in a blink of the eye
When your trouble shooting things and doing lots of back to back reboots - the frustration saved is massive!!!
Oh yeah, storing your picture viewer thumbnails on the OS SSD is mighty nice too, especially when your thumbnail cache is over 1GB
SSD are pretty affordable right now. Even the slowest and cheapest SSD still has the super quick multitasking access time
Backing up my 130GB OS partition from a Samsung 1TB HD to a 2TB F4 used to take about 25-30mins at 85-100mb a second with standard compression, with the fastest software for such - Shadow Protect. The same from SSD to a 3Tb Seagate does it in 8-10mins at 150-160mb a second with high compression
So I actually back up more often and it's no longer annoying