Yes you may, but I got error code 80070241 but could solve the problem like this: From within 6801 Make a new folder like C:\W7, or something you like.
Open command line window in your dvd rom drive. In the command line, for copy all files, launch first: xcopy /E /T *.* c:\W7 and after: xcopy /E /H *.* c:\W7
Open a second command line window in folder C:\W7
for last launch the command: ATTRIB -R C:W7\*.* /S
Now, close command line panels... and runsetup.exe form c:\W7\sources
You do need a copy of Windows 7 beta release. And you only use the command line utility in Windows... (cmd.exe) This way I described copy all files i a correct way to your harddrive, and you do the upgrade from there.
But this is not a way to do the installation, if I can recommend something... It takes a very long time to upgrade the system from 6801 to beta and not every program works. I think it will be better i you make a backup of all the files you need with Windows 7 backup system and then do a fresh install of the system.
It took me 25 minutes do do a full system install from the files on the harddrive, and 3,5 hour to do the upgrade and still needed to reinstall most of the software. So, do a fresh install and then you have the backuped files... p.o.c
Hope you can understand what I meen because english is not my native language.
Is there any particular reason why you would want to upgrade rather then do a clean install? Clean install is a much better idea in general but especially when going from a pre-beta to a beta release.. Not to mention clean installs of Windows 7 take about 20 mins on a fairly modern system.. upgrades take about 30-40 mins...
The upgrade worked on one of my computers without the need for the command prompt commands provided. I did it just to see what would happen and it worked perfectly.