The question is more difficult as it sounds. I have seen many people make a mistake in their answer to this one, and later walk away from an interview with their head bent.
Everyone can boast about their skills, saying they can do everything in MS Word, or in MS Excel.
And it would be right to say so, if these candidates delivered on their promises.
What we have often done in interviews, and what many companies and recruitment agencies still do, is asking the applicants to actually work with the computer.
In our interviews they had to do a few simple jobs in MS Excel, or typewrite a page of text to MS Word, and format the text according to the format on the printed page.
This helped us to see how fast they typed, and if they knew the software, or struggled to find the things they needed to complete the task we assigned them.
Many job candidates, who said that they were excellent with MS Office, could actually not finish the tasks. Needless to say, we did not hire them, becasue we doubted their words and interview answers. We did not trust them anymore.
To avoid the same scenario in your interview, I suggest you to not overrate your computer skills once they ask you about them. Say less, show more.
I have been working with MS Word and MS Excel for the past five years. I have used the software at school and also in my last job. While I do not consider myself an expert, and can not use every function the software offers, I believe I have decent computer skills.