Sometimes at places like blockbuster and other movie stores they have series on DVD's so you can rent them and watch them as much as you feel like it without the commercials.
Sometimes it is found on direct tv channels tv classics or hallmark.
Best buy. Has all the Seasons 1-9 my mom has all of em. Plus they come with a little book or whatever with them..
I think you can watch it at hulu.com. If you want to watch it without troubles and virus. You can try dvd sets at www.dvdbestonline.com.