to worry about."

You have to know and understand the criticality and possible duplicity of your job, and can it be done from the acquirer's location. My experience has taught me that if it can be done from the acquirer's own location, you're job will be moved.

In general, in most acquisitions, most of the core operational jobs are safe (an exception to this is when the acquiring company could easily assume operations). A little less safe are the production managers. The service/support (i.e. non-production or development) positions are usually at significant risk.

That's just a high-level statement.