By far and away the easiest way to get Movies onto the PSP.
Yes, you'll need 3rd party software to get around the copy-protection on commercial DVDs but you'd expect that anyway. AnyDVD from Slysoft works a treat.
I've had no problems with quality whatsoever. Only reason for not giving 5 stars is the time it takes to recode the movie then get it onto your PSP - about 2 hours on my, admittedly not very-powerful AMD Athlon 1.86GHZ, machine. I have no idea if other software is quicker. I suspect not.
So, you really have to buy 2 programmes to get the full benefit of this product but that initial cost will be far less than the cost of purchasing all your fav movies in UMD format - especially if you already own them on DVD.
Also, once converted, the movie files can live on your PCs harddrive as a "library" (they don't take up much space once compressed) for you to dip into whenever you want to watch a particular movie on the move.