If your screen wasn't flipping out I'd say your HDD has gone out.
When the HDD goes out you'll get this screen but it won't be able to boot so it will just be stuck, or restart and try again.
The screen you're seeing is different.. that suggests a graphics card problem to me.
I know the genius bar has this diagnosis rig set up at the Apple Store. They simply plug your computer up to it and hit 'run' and it outputs a list of statuses on all the hardware on your device. I don't believe they charge to do this (they didn't charge me to diagnose my battery problem). My suggestion is setup an appointment with them and have them help you diagnose what's wrong so you can then decide what to do from there.
Statistically harddrives have a life span of ~5 years, so you and I with our 2008 model MBP need to start preparing to upgrade :/ haha
hope that helps and good luck!