It's a Peace lily (Spathyphyllum wallisii). It likes bright to medium indirect light, being kept moist in summer and allowed to dry out in winter, and bring repotted every couple of years.
I was given one for my 18th by a school friend, and had it for many years before giving it to cuthbertcross' father (I think).
Feed it Baby Bio every couple of weeks in the growing season, and keep the leaves dusted for the best look.