If you wanted to make it easier on yourself just have both drives installed in the machine when you install Windows x64. It will generate the necessary changes to boot.ini. However, that doesn't seem to be an option seeing as you've already installed it.
You'll have to edit the boot.ini file on your primary hard drive and add an entry for the other OS. First, pick which hard drive is going to have the primary OS. Boot up off the secondary drive and print out (on paper) your boot.ini file. To do that:
Go to Start -> Settings -> Control Panel -> System
Click on Advanced tab
Click on Startup and Recovery button
Click the Edit button. Notepad will open up and you'll be looking at boot.ini.
Next, boot up off your primary drive and add a new line on your primary OS's boot.ini under [operating systems]. Copy the entry from [operating systems] under your secondary OS to this line.
This will only work if you didn't physically rearrange hard drives though if you did then you should read this about the syntax of boot.ini. Actually, you should read it anyway.
Comments
You'll have to edit the boot.ini file on your primary hard drive and add an entry for the other OS. First, pick which hard drive is going to have the primary OS. Boot up off the secondary drive and print out (on paper) your boot.ini file. To do that:
Go to Start -> Settings -> Control Panel -> System
Click on Advanced tab
Click on Startup and Recovery button
Click the Edit button. Notepad will open up and you'll be looking at boot.ini.
Next, boot up off your primary drive and add a new line on your primary OS's boot.ini under [operating systems]. Copy the entry from [operating systems] under your secondary OS to this line.
This will only work if you didn't physically rearrange hard drives though if you did then you should read this about the syntax of boot.ini. Actually, you should read it anyway.
Hope this helps.
-drasnor
EDIT. never mind. i say the other dual boot thread
-drasnor