I found two SATA3-plugs on my P55-UD5 motherboard and plugged an Intel X25-M 120gb SSD drive into one of the slots.

Blackmagic's Speed test reports an impressive 1.2 mbit/s read and 800 mbit/s write speed.
Vegas Pro 10c starts up in less than 3 seconds.
Screenshot attached.

That's nice. Vegas open for me in exactly three seconds also, but I use the older Western Digital disc drives. The place I like to see fast drives is my scratch drive, which helps AVCHD files play nicely.\\\

Glad you're happy with your fast drive Magnus, I'd like to get one also.

I friend alerted me to that this drive is the fastet thing you can buy today, "2,001 passmarks" which takes it to the top of the list - seek/access times makes a difference, other than raw data transfer

It is a Intel 510 series 120 GB SSD drive, model SSDSC2MH120A2

PassMark Software - Hard Drive Benchmark Charts (http://www.harddrivebenchmark.net/high_end_drives.html)

I also use the X25 for boot - probably the best single upgrade I've ever made to a computer.

However, my first one died during a spectacular thunderstorm - and my rig was connected through a continuous battery-powered UPS (1200 watt model). I think the intense electric field directly fried the SSD; nothing else in my computer was affected. Intel sent me a replacement pronto.

I also just last week lost another SSD (another brand). Just up and died. Still waiting for a return phone call for an RMA.

I wouldn't consider doing without an SSD boot disk, but they do seem to be a bit more unreliable than spinning disks. Be sure to keep an up-to-date image of your OS on a spinning disk.