Originally Posted by: Drew77For example I have heard guitarist say, alright play this lick in 4/4, alright now play it in 7/8... what does that mean, if your playing the same lick doesn't that mean its going to be the same no matter what time sig. it is in? I mean, you would count it differently and it may fit into a different number of measures or whatever, but it will sound the same won't it?[/quote]
Yes, you can count any piece of music in any time signature you desire. So you can play "Mary had a little lamb" and count in 7 if you want. The song will of course (as you point out) sound the same.

The reason to use any specific, given time signature is to create conceptual & perceptual clarity. So you should only use 7/8 if the melody you are playing is actually in 7/8. "Mary had a little lamb" is actually in 4 so you should write it out and count it in 4 so that it makes sense.

It is possible to rearrange "Mary had a little lamb" so that you can play it in 7/8. But it would obviously sound slightly disjointed and the point is that it would not be the actual tune but a slight rhythmic rearrangement.
[QUOTE=Drew77]Maybe it is just as simple as accenting different notes as in, for 4/4 you accent the 1 beat, and in a 7/8 the 1 beat would be in a different place, but that doesn't seem right because you don't always want to accent the 1 beat... I don't know someone help me out.

No, the accent is a completely different issue. You can accent any given beat you want in any time signature. You are right in thinking that "doesn't seem right"! :)

The time signature simply tells you the fundmental rhythmic background of a piece. See my tutorial here: Learning to read music tutorial

And the specific lesson on time signatures in that tutorial is here: Time Signature lesson

Hope this helps. Let me know!