MobileMe is being terminated in two weeks. If you have files on your iDisk which are not also on your computer you need to be downloading them as soon as possible or you will lose them.
You can migrate to iCloud and set Mail up manually to receive your @me.com mail:
You will not be able to sync calendars or contacts. If you want to have general online file storage you will need to find a third-party alternative - this page examines some options: