You either need to install the beta/RC and upgrade later, or wait till october 22, when its released. RTM is for MSDN and technet subscribers only.
I've heard (And Vista worked like this) you can just input your retail key into your RC version, and it will extend the license past march. The only downside is you may have some beta/RC leftovers. I imagine a lot of that will be patched out, but you may also miss out on some goodies that retail ships with that RC didnt. Either way, it will let you use your PC after March without reinstalling windows.
Acording to the microsoft web site the RC can not be upgraded to retail, by entering a key you have to uninstall then reinstall win 7 once you purchese it.
Just a heads up: http://www.computerworld.com/s/article/9136295/Microsoft_takes_Windows_7_RTM_public_on_Thursday?taxonomyId=1
You can download RTM legally, but you will need to input a legally purchased activation code once you purchase your final product October 22.
EDIT: As an aside, a better place to find more informed answers would be a place like http://www.sevenforums.com
Yes. I found that and downloaded and went to install on second partition then it asked me for key
so i guess ill just wait for retail, i dont need to pirate it just wanted to test it out, and not up for using the RC version since I cant upgrade it to retail would be kinda waste of time to set it up...
Another question about windows. Right now I am on Win Vista 32 bit, I am thinking about getting 64bit Win 7, I am pretty sure my processor is 64 bit set up, i checked out AMD website for the one i have and says it is. But I want to know what is the major differance between 32 bit and 64 bit I have been unable to find a clear answer in my research.