Primary Active USB flash and external hard drives

I'm running Win 7 Ultimate on an Intel i7 box.

I have a 1.5 tb C: drive marked by DD as "Healthy, Boot"

Also attached are:-

A Seagate USB drive attached by an ESAT cable - marked "Healthy, Active"
Two USB flash drives each also marked "Healthy, Active"

HOWEVER
There are also another USB flash drive and a LaCie 1 tb external USB drive marked only "Healthy"

The flash drives are FAT32 and the external hard drives are NTFS.

All of these external devices have previously been used on my old XP SP3 machine, which I still have. If I take one of the flash drives and put in into the XP box, it too shows up as "Healthy, Active".

I have two questions.

Firstly, how/why are these external drives marked as Active, which I understand to mean that they have some form of system or boot information on them. I know that the flash drives definitely do not, and I am pretty sure the other external hard drive doesn't either.

Secondly, I don't (touch wood) seem to have any problems with these being marked thus, and of course being external they can all be unplugged to leave only the onboard system drive. Is it OK to leave them as they are i.e. Healthy Active or should I mark them Inactive with DD?