Dual Boot, Quick Boot Boot.ini File Settings.
You might want to take a look at the Virtual PC and Virtual Desktop sections before you put to much time and money into a dual, quad, booting system.
I've had up to 6 OS boots but the issue was physical hard drive space and the time it took to switch. That was in the old days of development. Today I run 7 virtual desktops ranging from Windows XP to Server 2008 R2 on the same Windows 7 Ultimage system. Nice when all you have to do is switch screens.
NT systems offer multiple boot options. NT like your XP , Vista and MS 7 offer the same because they are built on the NT foundation.
A standard Boot.ini file:
[boot loader] timeout=30 default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS [operating systems] multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Home Edition" =optin /fastdetect
The above is setup to bypass the OS selection menu screen.
This is the fastest boot.ini configuration from start up to start button display.
Multiple Boot Options:
[boot loader] timeout=30 default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS [operating systems] multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Home Edition" /noexecute=optin /fastdetect multi(0)disk(0)rdisk(0)partition(2)\WINNT="Microsoft Windows 2000 Pro" /fastdetect /NoExecute=OptIn multi(0)disk(0)rdisk(0)partition(3)\WINDOWS0="Microsoft Windows XP Professional" =optin /fastdetect
In this example you will be offered the OS Selection of XP Home, Windows 2000 Pro or XP Pro.
The Timer is setup for 30 seconds which can be changed.
The Default boot application in this case is Windows XP Pro.
You can see the link without the /noexecute=optin.
You can only have one =optin in your boot list.
If you install different operating systems edit your Boot.ini file to point to the operating systems folder.
In the Example you will see the following.
These are the locations of your operating system.
If you add another OS like Windows 98 install the Windows 98 system into a folder named WIN98
Then edit your Boot.INI file.
Problem with non NT systems you will have to use FAT32 file system.
Best method to use is to add additional hard drives to your system formatted to match the OS.
When you install to additional drives you will see the rdisk(0) change to rdisk(1) etc.
If you have any questions on how to setup Multiple boot systems login and ask.