Blackbird has given you a great link, but it is time to tell us how comfortable you feel in konsole. I get the impression you are quite comfortable here.
Would be very handy if you have second pc you can practice on, a bit less nerve racking than when you are at risk loosing valuable data. Did you notice blackbird's signature
if you are one of those with similar inclinations you guaranteed will have fun.
Now I think you have figured out that if you try to mount a device that is already mounted you get a message saying this is the case and gives you the mount point directory (file place holder, in linux an item like a hard drive is just a file, that is a bit hard to swallow
If you have the time my guess is that you will 'easily' be able to fix your system to running stage, only a little bit in the fdisk -l that have me concerned. I think it is recommended you spend more time and straighten out the drives, which will include following.
It has BootItNG in a separate partition to help boot between Windows XP and PCLinuxOS as well as the PCLinuxOS partitions and a NTFS partition for XP. Both the secondary hard drive and external hard drive are formatted in FAT32 to make it easier to use these drives to access files in both Linux and Windows XP.
BootItNG, is your boot manager I assume, (looks like a hefty piece of software) and GRUB is a boot manager, I think those two are having a stand off, this is probably where the first step to fix now may be. Or do you have that part working well. Could also ask which Boot Manager are you using, and which one do you insist on using? (I am asking almost the same as blackbird) GRUB can easily handle the job alone, but this may not leave you comfortable.
A bit of planning now will pay off. Go over again what you aim is and then think of path of implementation.
Will Linux be you main system in the future or is it to play second fiddle for experimenting.