The command you typed - wuauclt.exe / updatenow - has an extra space in it. There should not be a space after the forward slash (/). Not sure if you just made a typo in this post, or if you were trying to run the command with that extra space. The correct command is wuauclt.exe /updatenow. The trick is, open the administrative command prompt, type the command, go to Windows Update, click check for updates, and then immediately hit enter in the command prompt window, to force the update to download. (An administrative command prompt will have C:WINDOWSsystem32> at the blinking cursor.) But, you've got the download coming through now, so that's not an issue any more.
Leftovers from deleted user accounts can cause it to "puke". Leftovers from older/previous VPNs can cause it to "puke". Incompatible drivers can cause it to "puke". Having external drives attached will cause it to "puke". Having a third-party antivirus installed will also cause it to "puke". Bloatware from OEMs can cause it to "puke". Personally, if it's giving you that much trouble to automatically update, either update from a clean install of W7, or wait a month or two, until more of the obscure upgrade bugs are identified and squashed, and your upgrade comes through successfully. There's a reason it's not upgrading on your system(s). Could be that forcing an upgrade at this point will leave you worse off than keeping the old OS for a while longer. Upgrading from a clean install of W7 will make life easier for you in the long run, I think.