I have one like this (though mine's a Braun not a Phillips)
Look for one with a decent amount of wattage if you go for one like this - at least 400W (mine's got 600W) so that it's strong enough to crush ice cubes - that way you can blend your shake with ice and make them more like smoothies.
I love the Magic Bullet. It is great, it mashes ice and the best bit is, you put a lid on it and you drink straight out of the cup so it saves on washing up. It is difficult to explain but fab. You can also get them cheaper (new) from Ebay.