I am installing Windows 8.1 on my HP G62 work laptop because Windows 7 ran out of support. Everytime I try to install, it says Download can not complete. Once I was so close, but it failed. If your curious, it's running Windows 7 Ultimate 32-bit. The processor is a Intel Core i3 with 4 gb of RAM.
I would also skip 8.1 and go straight to Windows 10. As basefisher stated Windows 7 will work on a Windows 10 activation. Microsoft retroactively upgraded all Windows 7 licenses to Windows 10.
Also depending on the stay of the current operating system an upgrade may not be possible (I.E operating system corruption, software or devices interfering with the upgrade). Backing up data and performing a clean install is preferential.
I used Windows 10 installer when 8 didn't work but when it was at the last stage of updating onto Windows 10, I let it sit for 45 minutes and when I came back it was back at 7 saying that it failed.