So I presume that you meant openSUSE installer and the answer is yes, but. A hidden Partition is just another partition on the disk and not really hidden exactly. It will be left alone if the openSUSE installer can find room to install openSUSE. It will try to shrink Windows if it can, but it may suggest a delete if it can not make enough room. I suggest you have a look at my blog on Partitioning.
Your disk sounds like an MBR disk, and you can only have four primary partitions on that disk. One of the Primary partitions can be an extended one and you can have many Logical Partitions inside that one extended partition. openSUSE normally wants to create three partitions and if you have two or more existing ones on a standard MBR disk as you do, an added Extended Partition must be created, but where will it be located and how much free space can it get without manual intervention on your part? IF your hard disk is full of Windows and it can not make room for openSUSE, then something must go or you need a new bigger hard drive or a second, external hard drive for instance.
I am about to install openSuSE alongside Windows 7 on my Toshiba Satellite laptop.
There’s a hidden factory installed partition from which Windows can be recovered/restored/repaired in the event of a serious problem with the OS. Question:
When the PCLinuxOS installer partitions the HD to make space for itself, will it leave, as it should, the hidden Windows partition untouched?
Your question is quite confusing, but yes, both the openSUSE and the PCLinuxOS installers will by default leave your ‘hidden factory installed partition’ untouched unless you specifically choose to format it. (You should at a minimum create free space from within windows for Linux, and to do it properly you should then create the partitions you want for Linux in that space with Linux tools before installing Linux, (but most take people shortcuts)).
An extra point here is, to make things easier if you have windows and want to add PCLinuxOS and openSUSE,
to avoid bootloader issues, install PCLinuxOS before openSUSE, The PCLinuxOS boot loader will not, by default recognize openSUSE (at least in my recent experience),
However, If you decide on installing openSUSE before PCLinuxOS It is easy to fix.
True, but prevention is always the better cure. Legacy Grub still works well for openSUSE. It can even boot a recent Grub2 installed to a logical partition here. PCLOS always installed smoothly and completely OOTB, in my experience, so I can understand the fans.