I was under the impression that Easter came from Ishtar, because of the other associations with Easter of Easter eggs and bunny rabbits (both fertility symbols), but the information at Answers.com call that into question.
The name Eostre also bears some resemblance to the name Ishtar, a Babylonian goddess. Other variants on Ishtar include Astarte and Ashtoreth. This resemblance has resulted in some Neopagans and Christians opposed to Easter believing that Easter is Ishtar's festival. (Fakelore is often constructed to support such speculative continuities.) There is, however, no evidence that Ishtar was ever worshipped in Europe, nor any strong evidence that the myths of the two goddesses were related.
Whatever the origin of Easter, Christians should celebrate the Resurrection. Celebrating it on a day that started as a pagan holiday does not negate its importance or value.