I have a question about lifting.

Lets say your doing two muscle groups - Arms, and back for example -- 4 lifts each.

Is it better to do 4 lifts on one muscle group and then 4 on the other (example: arms, arms, arms, arms, back, back, back, back)

or to rotate? Arms, Back, Arms, etc...

or does it matter too much?

Depends on your lifting philosophy and what you are trying to acomplish. Rotating may result in more rest between arm exersices or it might not if you are supersetting.

If you are training max strength and doing sets of less than 3 reps with more than 90% 1RM, I wouldn't recommend alternating because you will just confuse your nervous system and may not be able to lift with good form if you keep changing what you are doing.

If you are trying to gain endurance, supersetting with short rests can work great. In this case you can take 1 min rests or less, between exersices, but rest each muscle group for more than 2 mins. Also potentially good if you are short on time.

If you are resting more that 3 minutes and doing less than 90% of your 1RM, it probably doen't make that much difference.

I am new to lifting, so I don't know if one is necessarily better than the other. I personally switch back and forth between both from week to week, it may be mental, but I feel that I am constantly "shocking" my muscles by doing this. One week I will go straight through, the next I will alternate super-set style. I think it will just depend on your style and what works best for you.