I congratulate you
Pretty nice games you got there, and it was a great deal. However, I highly recommend you leave the strategy guides for later. finish the games by yourself and discover all the secrets you can by yourself. It is just pointless and stupid to finish a game with a strategy guide. But it's tite when you use it after having tried a lot and when you want to "kill" the game, by then, use it. Well, at least that's my recommendation
But to tell you the truth, both games are damn short. Of course Onimusha is way too short, but so is FFX for being a RPG, which disappointed me a little. And hell, yeah, definitely a must have is MGS2, it is just way too good, yet too short as well
And I do recommend Devil May Cry for a future buy, if you liked Onimusha