Installed Windows 10 first time and went back to Windows 7 because it had some problems with starting. I thought it may be due to a corrupted copy as is stopped many times when downloading. Downloaded again from update and installed to 51% and said it had a problem and went back to Windows7 automatically but had to repair before it could start again.

Could it be I got a corrupted copy from download as my internet speed is not good or do I have a problem with Windows 7? Should I re-install Windows 7 or get a copy of Windows 10 from another source?

Here's a good read on that. Some are experiencing it. You probably want to download the media tool, put it onto a thumb drive and boot and install from that.

LINK

Yeah, don't boot from the thumb drive. Boot up a completely updated Windows 7 installation and then run the Win 10 upgrade from within Win 7. Until you upgrade your Win 7 or Win 8 with Windows 10, windows 10 can not be activated. The computer will be "remembered" after the upgrade and you can then do a fresh install of Win 10 if you want.