KR - You really didn't give many good power metal suggestions.
Good power metal groups include: Blind Guardian, Rhapsody, Nightwish, Dragonheart, Luca Turilli, Sonata Arctica, and Angra. (Nightwish and Angra are less power-metalish)
Power metal is generally faster metal, but with vocals more like progressive metal, almost always clean, and oftentimes having harmonies. Lyrics are often fantasy medieval age based (Rhapsody is a really good example of this, so is Luca Turilli to a lesser extent). The sound is fairly unique, and powerful, but from group to group you can hear many similarites. 2 guitars playing simultanteously and interacting in a non soling manner can be common and very interesting (Dragonheart does this very well). The best part of power metal is the singing, the choruses just fit in with the powerful, fast guitar (Usually well played, often in a galloping style). I would reccomend Blind Guardian - Nightfall in Middle Earth to start with, it is an extremely good CD based on a Tolken book.
Well, I guess there are two schools of power metal, the more serious "normal" type like Gamma Ray and Stratovarious and the fantasy based Rhapsody, Blind Guardian, etc.
The fantasy style ones are much better IMO. The lyrics are usually horribly cheesy (Not Manowar bad, but still pretty bad), but the music itself is just so damn cool.
DarkAngel - my favorite song would have to be Via Nocturne on Deggial, it is the 10th track. It starts off with a darkish sounding organ, some strings kick in, and then the guitar, slow and galloping, almost power-metal style but darker and slower, and then the vocals. And then the rest of the song plays and all is good.
And noone is saying anything about Symphony X. Someone should at least download an mp3, they are extremely good.