Given that 88 percent of surveyed companies admit they have a "problem" with legacy applications (57 percent rated the problem as serious) if you haven't yet started planning your application migration strategy now's the time.
Or you can just stick your head in the sand and hope for the best.
Given you don't want a mouthful of sand, here's some things you might want to include in your plan.
At the 30,000 foot level, the main task of planning for your migration is really really understanding the application and all its interactions. It's a lot of "what" and "how" questions and very little "why."
- does the app do?
- data does it create?
- data does it connect to?
- OS does it run on?
- language is it written in?
- many external references?
- many lines of code?
- 3rd party controls/components?
- many of those controls will run on the target?
- does the application fit into the overall business process?