Trying to boot Linux on separate disk

I have an internal PATA disk0 with 3 ntfs partitions followed by 2 ext3 partitions and a swap partition on which I have installed ubuntu 9.10. This was an upgrade from 9.04 and GrubLegacy is still being used. There is GrubLegacy boot code installed in the MBR (and following sectors) of disk0. The Windows Disk Management utility erroneously reports these linux partitions as being ' Primary', instead of the correct ' Logical' appellation. The first ntfs partition on disk0 has the active flag set in the partition table, but there has never been any OS installed on disk0 except ubuntu/grub, which I understand neither sets nor uses this flag.

I have a second internal SATA disk1 with 3 ntfs partitions followed by 3 unformatted (Raw) ones (which are reported to be FAT-16 by EasyBCD). The first ntfs partition (which is 'active') contains my Vista installation, and is booted by custom OEM code in the MBR and following disk sectors of disk1.

Booting the machine from disk0 (as set in BIOS) gives me the Grub bootmenu, from which I
can boot either Ubuntu or Vista. Booting the machine from disk1 results in a normal startup
of Vista (by way of the Boot Manager menu if so configured). I am seeking to use EasyBcd to
give me a Windows Boot Manager boot menu entry from which I can boot Ubuntu. I have gone through the Add New Entry dialog in EasyBCD , but using the boot menu entry created
that way gives only a black screen with an eternally blinking hyphen, and I must then power
off my computer. I also note that the c:\NST\nst-linux.mbr file created by EasyBCD consists
of 512 Null bytes, which surely cannot be correct?
Remember to tick "grub isn't...." when Linux and Windows are on separate HDDs (as described in the sticky)
"Active" is necessary regardless of the OS. It's the flag that the MBR looks for, to locate the boot sector containing the next link in the boot chain.
Well, I was reluctant to check that box because it would be counterfactual, assuming it is
referring to the MBR of the disk which contains my Linux partition. Am I to assume, then, that
what I'm trying to do is unsupported? It was not quite clear from the available documentation
that my scenario , while not specifically being mentioned, was actually not possible. I will
look into reinstalling Grub to my Linux partition only, or perhaps converting to Grub2. Thanks
for the help.
No, it's referring to the MBR being used to boot the system running EasyBCD, and strictly speaking it's not an all-inclusive label, more shorthand.
There's not room on the page to describe exactly when and why you should use the box, but as the sticky explains, Legacy grub+different HDD=tick the box.
That creates a bridge between the two bootloaders with Neogrub because of a Linux problem when it's not on the first BIOS HDD in the boot sequence.