All of these leaked builds are just daily/interim builds that hold no real drastic changes at all.. Small improvements in speed and overall performance coupled with a larger driver database are all they bring to the table so far.. In my opinion it is a waste of time and bandwitdh to download them.. As loathe said, the RC works perfectly fine and I would also recommend sticking with it until the Retail Version shows it's face.. The RTM will be released (NOT TO THE GENERAL PUBLIC) very soon and the Final Retail version of Windows 7 will be released on October 22nd, 2009..
The RC is still available at the Microsoft Windows 7 site and will be at least through July and doesn't expire until March 2010...
The next public release of 7 will be when you see it on the shelves mate. There may be minor updates through Windows update at some stage, there may not be too.