If I move from Oregon to Washington will sale of company stock still be taxed in Oregon if I am still working in Oregon? Does anyone know where you to go to find the Oregon State tax rules regarding the taxation of Washington residents?

If you live in Washington and work in Oregon then only Oregon sources of income are taxed by Oregon. For most people this means your wages from your Oregon job. Capital gains on sale of stock, dividends, interest, etc are not taxable by Oregon for Washingon residents (this assumes that you are talking about sales of stock in a publically-held company).

Here are the instructions for Oregon Form 40-N, which is the tax form for non-residents:

http://egov.oregon.gov/DOR/PERTAX/docs/2008Forms/101-045-08.pdf

Note that on page 5 it specifies what is, and is not, Oregon income for non-residents.

The year you move from Oregon to Washington, you may still be considered resident of Oregon. Check Oregon residency requirements at the state web site.