Sorry for being late to the party, but did you check and try out some various options which might be available for you in the bios section regarding drive settings and or boot options and behavior? I remember using my dekstop pc with win7, never had a prob , updated to win 10 and then i seriously got stuck in a mode where it kept telling me that i got no bootable drive inserted - after updating the bios  - tadaaaa - the boot manager recognized the drive and all good. One thing to keep in mind - if i am right - this device here is from 2008??? I did successfully replace old HDDS on 3 different notebooks with new SSDs, but none of these was older than 2012 - and they had at least win 7 or win 8.1 on them - did upgrade all of them with new ram and fan cleaning and such - windows 10 working like it was always meant to do so. In my personal opinion  - what is the latest date in terms of drivers and bios updates and such regarding this unit there? Did you install the support assist and have Dell check the unit for latest drivers and bios update and such? Does this work at all? It might be a really tough task getting such an old unit get to work the right way with win 10 - i think it is possible, but personally i dont think that your boot sector is really messed up - rather more like a compatibility old bios / hw - interface thing. Most of the hard drives are backwards compatible - but that is not a 100% guarantee that everything will work fine. Also i did find this older thread here , might help as well? [URL]   All the best - i know the feeling of wanting to keep older hardware to stay alive - especially in a modern throwaway society! Cheers Fullyard  
An older lady donated this laptop to me to fix up.  It's in perfect original condition.  I installed a new 240 GB SSD from Crucial and newer Intel wireless card.   I got the "No boot sector on internal hard drive" when initially installing Windows 10 from the USB drive.  By pressing F1, Windows 10 installed perfectly.   I'm using this laptop now (as I'm typing) and it works perfectly.  My only problem with it is that every 10th boot or so (unpredictable) it will not boot and show the "No boot sector on internal hard drive" again.  By using F1 it will boot to Windows fine again.   I'm pretty sure this can be fixed by fixing the boot sector, but I hesitate to do it until I'm sure how to do it and would appreciate any help or advise on this.  Thanks
No boot sector on internal hard drive