I used around 20 minute installed Xubuntu on my dad's Thinkpad T60, and use around 4 hours to fix the problem it bring me
I have to make sure my dad doesn't know that I secretly mounted another OS on his computer, even he don't know what OS does, he just don't like me to do anything other than "using word" on the computer.
Because in this space, I got totally confused.
What does it mean by new partition size? The size of the partition to install Xubuntu or the size for the original partition.
I thought it was the partition to install Xubuntu and make the size to the minimal possible. You guessed, it's NOT!

After I installed Xubuntu and did some cleaning up (configure Guru so no one see any apparent difference in start up), I login into Windows and found the mistake I made during the installation.
Hell begins.

Partition magic!
Some second later…
Init failed Error 117 Partition drive letter cannot be identified

Obviously, there is something wrong with the partition table, if Xubuntu did something to it, there might be some software in Xubuntu can fix it.
Gparted and QTparted both give me the same error: Overlapping of partition.
Dude… that's not cool…
So I go around search the net, believing the only way to save my life from my Nazi-Communist-“no computer for you!” Dad is to use the Windows Rescue Console’s fixmbr and fixboot commands recommended by the tech guy…
Imagine here is what I have to go though

Mgccl: Dude. Some overlapping of partition is going on!
Tech Guy: Right, maybe it's something to do with MBR and Boot. Get your windows install disk, and when it pumpt for a choice, press R to go to rescure console
Mgccl: but it says can't find hard disk.
Tech Guy: U HD FUBAR
Mgccl: What now?
Tech Guy: Do a back up and format the entire disk.
Mgccl: But I don't have enough time to do that, my Dad is coming back any second, and my sister is bitching and moaning about it for the entire afternoon.
Tech Guy: Well, you are screwed.

So here is the final solution:
1. Get Partition Table Doctor, let it auto fix the problems
2. Then Paragon Partition Manager do the partition because Partition Magic does still getting the error.