it's good for it to get some partial moving sunlight, just not hot noon sun. but northen window is fine. if the new leaves are turning yellow it might be from incorrect watering - do not allow it to dry up more then half way down. but allow the surface to feel somewhat dry to touch before watering. it's a fern, so it likes higher humidity. if you have hot dry air blowing on it from a heating vent or radiator that would be bad. they don't like to be disturbed. it might decline severely if you bare-root it. sizewise current pot looks ok to me. how long have you had it? it looks fresh from the shop. you can uppot it though to the next size up (1" more around the rim, so 2" more in diameter) : put down 1-2" of fresh mix in the bottom of a bigger pot, position the existing pot in an empty bigger pot and fill in soil mix around it. spoon helps :), followed by a chopstick to push it down. then rock the inner pot side to side and lift it - you should have an outer layer of soil holding shape like a mold. it's good to moisten the new mix a bit for this to happen. then you lift the plant from the old pot and carefully drop it into it's soil mold. minimal disturbance of roots. or you can first lift the plant from it's pot and work with empty old pot - it's easier to push the soil around the rim then.

OK, I think I've got it! Keep your fingers crossed for me.. the pic should be below. Pardon the quality as I had shrunk the pic to post in the forum, but ended up giving Flickr a try. Here is a link that might be useful: fern-esque picture

What you have, could be the Fern I found at a local nursery that looked like an Asplenium and was labeled "Alligator Fern". It actually was a Polypodium musifolium, a/k/a Microsorium musifolium 'Crocodyllus'. Check the link for clickable thumbnails and see if it is the same. Mine has been growing under lights in the basement since it was brought indoors more than 2 months age and seems to tolerate that environment, even though the forgetful owner doesn't water it very often. Rb Here is a link that might be useful: Microsorium musifolium 'Crocodyllus'

Tree of Heaven, Balm of Gilead, Bam, Does it look like this? If so, it is highly invasive and sends out tenacious roots and the darn things pop up all over. Jerking them out doesn't work, but Round-up does.