[lubuntu] Dual booting with 2 HDD

I somewhat new to this so this is where I was coming from. I tried out Lubuntu 14.04 LTS last year on Virtual Box while mimicking what my PC of choice would be like ruing it and I ended up liking it. However with the complicated position I'm currently in my family members would flat out refuse to adapt to Lubuntu since my parents constantly uses a printer that would only work with Windows and my brother some some geeky stuff that also only works with Windows. So now since not only the latest LTS came out today but I just got my secondary HDD in the mail today too. So I would like to dual boot my older computer rig from 2007, but I am a little uneasy on going through with it.

Let me explain why. My PC of choice that I am currently going to follow through with this runs Windows XP but the place that I got it from refused to give me the boot disc without making me pay for it. They might of well stop supporting it since XP hasn't been widely adopted since 2014. So with that out of the way I have no way to back up my stuff when I finally do this or even do a fresh reinstall sine I run the risk of losing 9 years of personal documents. so I would like to do this without touching the Partition of XP as much as possible so I don't end up having to reinstall the whole thing without having to resort to some shady stuff. So I know the risks of Dual Booting from one HDD so I opted for two to reduce the risks as much as possible. I also want to make the boot order to go as Lubuntu as the master while the slave being as Windows XP so I only have to run that when I have to. It not only makes it a little more of a pain for me to adapt to Lubuntu but both my parents would rather prefer Windows as their choice of OS. They would also not bother with the boot order and would have Windows to be prioritized over everything and I don't want them to think that way since XP is pretty much dead.

So this may take a good couple of days to plan it out on what I need to do to get it where I want it to be. My goals are to have my PC of choice to dual boot, but would like to have Lubuntu to be the primary OS and XP as a backup. I also don't want to screw with the MBR on XP at all, however if I don't have much of a choice I would have to take a risk and do it so the less the better. And the last part of this is to maintain this as much as possible while minimizing the risk of possible data loss without having to go through much struggle sine I am currently on a limited budget right now. If it going to get technical and complicated, then I wouldn't mind going through that path just to achieve my goal. If at any time it would seems like I would need a walk though, I wouldn't mind that either since I am not that familiar with any Linux Distributions since I started with Android back in 2013 for casual use, and Ubuntu probably back to like last October so. So I can't say that I know it very well but have worked with it in the past just to get by.

This is my PC specs of the build I would like to do this on:

Operating System: Windows XP Home Edition 32-bit SP3
CPU: AMD Athlon 64 X2 4400+
RAM: 2x 1.00GB Single-Chael DDR2 860MHz
Motherboard: ASUSTeK Computer INC. M2N
Graphics: 320MB EVGA NVIDIA GeForce 8800 GTS
Storage: 149GB Weste Digital WDC WD1600JS-61MHB1
Optical Drives: LITE-ON LTR-52327S
Audio: SoundMAX Integrated Digital HD Audio
Network: Nvidia Integrated chipset

And the HDD I'm going to install Lubuntu on (either 14.04 LTS or 16.04 LTS): Seagate ST3250310CS 250GB 7200RPM 8MB Cache SATA 3.5