How to find Boot Drive

you can find this info on the boot.ini file on your drive that contains the MBR (C:).

Can you explain me some more details plz.
i.e i my pc the content of boot.ini file is

[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(2)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(2)\WINDOWS="Microsoft Windows XP Professional" /fastdetect /NoExecute=OptIn


With this information how i arrive that the boot drive is C: or D:

this says that the time to display all operating systems installed on your computer (for you to choose one) is 30 seconds.

the default operating system to load (after 30 secs if you do not change something in the selection).

You can read more on : http://support.microsoft.com/kb/99743

with only 1 disk, i have the following boot loader :
[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 Professional" /noexecute=optin /fastdetect
----
so you are booting from disk 0 (just like me) but from partition 2 (i have only 1)
is that clear enough ?

Thanks you so much for your reply.

So if i change disk(0) as disk(1) ,then it means the boot drive is 'D'?

But after doing the above changes, i have checked with IS Scrpt (Install Shield) to find the boot drive. But it still says boot drive is 'C:'

If possible,  can you plz provide vb/vb.net code to find it programatically?

when the system boots there is no C: or D: - these are parts of the operating system and can be changed.

if you want to boot from another disk, you need a boot manager like :  http://gag.sourceforge.net/
or : http://www.boot-us.com/

Your boot drive is just the main drive that the BIOS is going to read the "boot" files from ... your boot.ini just tells the boot files where to load the OS from ... you are still booting from the same drive.

If you want to change your boot drive, go into your BIOS settings and look for the boot options ... under the hard drive option it should give you the option of which physical drive you want as the "1st or primary" boot disk ... this is where you want to change it.

You could use a boot loaded ... this works by intercepting the BIOS call to the disk and then redirecting on the fly ... but takes additional configuration and if anything goes wrong with the boot loaded it could make your primary drive inaccessible.  That said ...a lot of people use them, espcially in the Linux world.