Selphy, guitar hero 3 is pretty hard compared to the rest imo, as I am a fan of Pull ons and hammers off. Also the slider gems. GH3 doesn't have that many which makes it hard at fast speeds. Especialy TTFAF. I cannot do that on medium on GH3, but can on greatest hits for that reason. Try, suck my kiss on medium. That is pretty easy, but not too easy. Or cities on flame with rock and roll.

Astarael, You find drums easier? Maybe you have better hand co-ordination vs finger co-ordination.

Also, can you play the old ps2 GH, GH2 on the PS3?
Some games (like singstar) I know had an update to let you play the older versions. My fave song on a guitar hero game I want to play but not sure if it will work. (Ziggy Stardust)