The previous owner left it when she moved out, and I'd love to be able to take care of it.
I believe your plant is Calathea lubbersii, which belongs to the Maranta group of plants. They are quite fussy about their cultural requirements, but whatever the owner (or you) have been doing has obviously been appropriate because the plant looks very healthy and is quite tall, though the depth of the pot may account for that as much as anything - my houseplant book says to plant this in relatively shallow but wide pots, but yours is doing just fine, and luckily, plants can't read.
This one's grown for its marked leaves, but the colours fade somewhat if the plant is exposed to direct sunlight all day, they are better with indirect, bright light, so a well lit sunless spot is best. Average warmth, but with a minimum temperature of 60degF, relatively high humidity levels (mist the plant regularly, specially in winter when the heating's on), keep the compost moist at all times (but not sitting permanently in water in an outer pot), reduce watering in winter, and preferably use soft, tepid water.
Some images of various Maranta/Calathea plants (including yours) in the link below, together with basic general care instructions