IANAL and I don't know about other countries, but in EU (definitely the country I live in and am pretty sure it goes for the rest as well) any non-compete agreement after two years is void by law.

You are required to hold confidential stuff for life, like business contracts, but you can use your know-how, if it does not violate any patents, in a competing company as you see fit. This knowledge is a part of you and cannot hold you against employment. Even if you do decide within those two years to employ yourself in competing company, this can be held back by your original company only if they give you X% of your pay at them (X can be 80, or as low as 50, as my friends inform me).

I've actually dealt with this in third-party IP cases I've consulted on. Of course a lot of "bench advice" best practices (use a debugger as a silly example) shouldn't cause a problem--or maybe even some various specific experiences about practices that worked. A file dump of corporate strategy and business plan presentations or code--even if they probably get pretty stale after a few years--probably not.