Bit of a technical question - i-Tunes

Be gentle with me I'm not the most technolically minded person!
I had an i-Tunes library on an old laptop and have now moved to a mac - most has moved across fine, but music I bought (not a lot thankfully) cannot be downlowded onto the ipod as it was bought on a previous machine IYSWIM.
Now I'm guessing that I just need to amend my settings or summat

I changed laptops and when I put my i-pod into the new one everything on it stayed the same. I was worried about loosing EVERYTHING I had downloaed but I was told that you can have your i-pod recognised on 2 machines and as I say mine still has the stuff I bought on it.

If you still have access to your old laptop you can copy the music files out of the itunes music folder on the laptop to the one on the mac.