A dual boot or multi boot computer allows you to do emergency repair faster and with more tools...
Can't think of any disadvantages off the top of my head, but then for advantages there are some.
If you have a multi startup for your computer you won't need an ERD to start the computer if your main Operating System crashes for some unknown reason, just restart and select the other OS and then troubleshoot why the other OS
BSOD'd. (Blue Screen Of Death for Windows).
For my Desktop and Laptop I have this capability. For the desktop I do some strange things while testing/experimenting with programs/hardware so having another OS is faster than using a ERD. With another OS you can do more than with an
Windows Seven ERD even ERD Commander or BartPE.
When I worked for a major company I traveled a lot, most of the time is was out to a site and back in a day, occasionally to a site for a day or more. Something I discovered while traveling you never know what is going to happen. Even though I carried all the software the company used with me at all times (it was in my backpack) having to reinstall an OS at midnight is not a good idea, you are tired after a fourteen hour day and will make mistakes. That is when I became a believer in a Dual Boot capable computer. Now I have dual boot on my laptop, if something happens to the main OS I have the secondary OS. Only a hardware failure will keep me from using the laptop.
Another factor in having a
dual boot system is the interface is familiar and it will be a lot faster than the ERD Commander/BartPE option.
You can run a check disk, install and run anti virus/trojan/spyware/malware programs from your secondary OS easier than with the two ERD's above.
The only thing you can not do as far a finding out why one of your OS's crashed is load the registry on a dual boot system. The registry editor will not load a OS registry that is not running. (ERD Commander gives you the option of starting or not starting the resident OS, BartPE just starts it).
As a long time tester/experimenter of hardware and software I know that sometimes a Virtual Machine will not work, either because the VM can not see the hardware such as a multifunction USB printer or some software will not load in a VM
such as Dragon Naturally Speaking (that was a waste of a half hour) so when the
new software or hardware takes the computer down instead of searching for that
elusive ERD (Emergency Repair Disk - see the
Self Computer Repair Unleashed
2nd Edition Manual for instructions on
making one) just restart and go to the other OS.
If you buy a new computer what do you did with the old one? Throw it away? Donate it? Did you wipe the hard drive first in either case? NO???
The 5 Steps to high quality and cheap
DIY Computer Repairs
Get It Today...
Oh boy! Well water under the bridge as they say...
Did you know that when you wiped the hard drive that the license for the OS
on that computer just became available for another computer, that is unless you
reinstalled the OS before donating it. If you didn't and have the source cd for
an installation you can use your old OS as you secondary boot system.
By using your old OS you will be familiar with the way it works, how much memory it uses and so forth. My only advice with this option is to not overload the OS with junk, just the minimum you think you would need to repair your main OS, AV, some other testing tools, shut down unneeded services and GP's (Group Policies). You don't even have to join a domain with this OS unless you keep your tools on a domain server.
One last thing about the secondary OS, if you plan on having it on a network that doesn't have a DHCP service don't use the same static IP that the other OS uses, this will cause problems with the DNS records.
Piece of cake...
This was the topic of a submission to my old Q and A about
Dual Boot a while back.
Why wouldn't you want it on your computer?