Yep you could do that if your Windows will boot, without being "repaired". It's less reliable however, because DOS & M$ Windows may overwrite your GRUB install, if it's on "their" disk.
Physically you can change the disk order by switching cables. Or you can install a Boot Manager to provide a menu, to boot Windows or GRUB on the 2nd disk.
There's a thread on booting Linux from Visita (XP?) on this forum, but that hasn't worked for me; I'm not sure if there's not a Vendor boot manager installed rather than the M$ one.