Alright let me try to clear this up and make it as understandable as possible.
Having multiple drives gets thigns a bit confusing. I will show you my setup:
You will notice i have 3 Hard drives. The first set of hard drives is my OS Drive. Vista, Win7 and the last 2 are the Swap and files for Kubuntu.
But notice how every drive on there is considered Active. This is because each one is technically active at one point or another. But the major thing to know is where the BOOT part falls. Cause that is what controls the boot. Mine is with my Win7 drive. So if i were to format that partition i would lose my boot.
Now my music drive is active as well as teh Storage drive. While the Pics, Docs and Data are not active.
Yet everything functions correctly as it should. There can be only 4 Primary partitions in use on any hard drive. From there they go to Extended and Logical Partitions.
Now the thing is if i wanted to install say XP to any of the 3 that are not active i could not. The partition has to be active for a OS to be installed to it but the partition doesnt have to be active to be used properly.
Like i said it is realy tough to just give a definate answer cause there really isnt one. The Active partition also helps the BIOS see the drive. So i oculd use my BIOS to boot from with the F12 option.
Start>Right Click on Computer (Or My Computer in XP) and select Manage. From there choose teh Disk Management option on the left. Post that screenshot. I will tell you if you are in any danger of causing your system not to reboot properly.
Basicaly the best i can say is that the Active designation is used by both Windows and the BIOS to show drives that can either be a.) recognized by the BIOS and used for Boot or b.) recognized by the BIOS as a drive that could be used for the install of a OS.
That is probably the best way i can say it.