What computer skills are most essential

for accounting? Excel? Access? Anything else? 

Just want to be better-equiped so I can sell myself quicker and at a better price should I need. A couple of recruiters approached me for jobs that requires both IT and Accounting backgrounds. I didn't go for 'cauze.... I know adding some computer skills can add weight to my resume, but I am not sure what skills exactly, and how to gain those skills.

Any suggestions are appreciated.