[Eonwe]

well, ill add my two cents.

i've always seen the "creation" of middle-earth/arda as two separate parts. (i don't know if this is how its supposed to be viewed, though i makes sense to me.) the first part is the three themes of music. in this section, Eru acts very much how I've always though God would. (except in teh judgment of melkor.) He is involved and active. there is more personal relationships, as he raises up manwe to combat melkor's cacophany. you could kind of see it as god and the angles here.

the next part is kind of wierd. he shows the ainur the vision of teh world, and then creates it. the valar go down into it and dwell there, along with their mia, and melkor. here it is kind of passed on to Manwe and the Valar. they become sort of like teh "god's", with their angles being miar. but you can't really make a comparision between them and God, i suppose.

it seems to me that Eru gave a "gift" to the Valar: to fastion arda into waht it was in the vision. i guess they can do whatever they want with it (ei. lets make a mountain range here, put some lamps there, etc., as the vision was rather vague, if i recall correctly.) Eru doesn't really have much to do with it, except in extreme matters, such as the destructino of Numenor.

so i would have to conclude that Eru doesn't act as "God" for middle-earth. i guess maybe he could for whatever region he dwells in with teh ainur.