Learning actionscript

I want to really learn actionscript and I’ve learned the basics of it in Flash 5 years back in college.

I don’t know how far flash has come since, in terms of its actionscript. I realize it’s more powerful, but I have the original actionscript reference guide book of flash 5 that came with the software. I was wondering, would this book still serve me as a good resource for me to learn it, but using flash mx 2004? Or is there a great deal of difference and additions?