Taking an LLC out of state

Hey,
Thinking of crossing the Red River into Oklahoma with my LLC to do some investing. If I purchase properties with my LLC do I have to register with the state as a foreign entity or whatever? If the process is anything like what I did in order to practice my profession in that state it may be easier to form an OK LLC. I had to fill out 8 pages of data, get a physicians OK, employment history from 1st job forward and notarized in about 6 places. Having a resident agent is no problem as my daughter lives in OK (tried to raise her right). Any ideas? Thanks.
Peace,
Richard

I live in colorado and invest in four other states and yes I have a business in all of them!!!

Hey,
Thanks for the reply. It would seem the proper thing to do to have a LLC, etc. for each state, especially with different tax set-ups in each state. Nice to see someone else burning midnight oil besides me. Thanks again.
Peace,
Richard