As another poster said, the enforce-ability of a non-compete depends on your state (province?). In general, the more broadly a non-compete is written, the more difficult it is to enforce.

From an enforce-ability standpoint one possible work around would be to take a job with the new company that is completely unrelated to the work you do for the consulting company. My company has done that in the past. For example, we may hire an accountant who has a non-compete and put them in the audit group for a year. Since the work is not the same, the agreements usually don't come into play.

This still, of course, leaves you with the internal and ethical dilemma. Nor does it account for the fact that it doesn't necessarily sound like a job that you would love to take (the notion of loving your job is probably over rated, but it helps).