Citrix

"Most of these companies will be heavily reliant on ancient legacy apps tied into Activex or some other crappy ms standard from a few years back."

Yeah, but they might now run them on Citrix or something, so that they don't have to deal with distributing software to desktop machines. In which case a Mac user just needs a Citrix client and a network connection.

Worst-case scenario, they can use VMWare or Parallels on the Mac. That's what I did when I worked for Accenture in 06-07, and had to run their time and expenses Windows app. (I was in their 'Technology Solutions' branch, not consulting, so I didn't have a company laptop. I just used my MacBook Pro.)