I dont know how great Dragon Quest is. I've never played it, and it doesn't look all that great among other RPGs, but I guess you never know. However it does come with a playable demo of Final Fantasy XII. That's definently a plus.
I played Half-Life 2 on PC. It's fun, but it wont last long. The only fun you'll have with it is with the gravity gun. Eventually you'll want to try out another gun, and you'll find out that when it comes right down to shooting and killing, it's really not all that great.
GTA: Liberty City Stories was very good in my opinion, but only if you spend a lot of time out of the house, and you plan to bring your PSP with you. If you're sitting around in the house with all your consoles there, then there are many other games that are much better. One thing I did like about Liberty City Stories though was the story of the game. I think the story is much better and more interesting than GTA3 and Vice City. Not San Andreas though, I really liked San Andreas' story.