Stop 0x0000007b while loading the Windows CD Rom or recovery disk
Wish I had a penny for every time I've seen this one. Quite common on Dell PCs when trying to load the Operating System again, this error can be easily solved. Boot into the BIOS (press F2 on startup on most dells, other PCs may require Del, F1 etc). Once in the BIOS, navigate to 'Drives' and change the SATA operation from "RAID Auto/AHCI" to "RAID Auto/ATA". Save and exit setup. On reboot you should be able to load the installation disk.
I'm seeing more and more boot sector viruses these days. The symptoms can be similar and give the exact same stop errors. An MBR fix can repair these but sometimes it is easy enough to pull the drive out and mount it in our test rigs, giving it a full scan for Viruses, Trojans, Spyware, Rootkits etc. Data recovery can be done at the same time so it can be quicker if you have a spare PC to do it this way.