It depends on the job requirements itself however as a generic statement Excel and Word are key for most administrative and knowledge worker jobs. MS Office (which is the combination of Word, Excel, Powerpoint and Outlook is a solid combination of skills to have)
Not only should a job seeker/hopeful moving-up-the-ranks employee have these skills, they should also be able to explain what they know to do within these programs. For instance just saying I know Excel is not as powerful or convincing as saying "I can set up formulas, add columns and set up new worksheets in Excel" or "I can set up new documents and do mailmerge in Word." When an employee or job seeker states what they can do with these programs its much more powerful!