If your are looking at HDD external USB boxes in the shop for around NT$1000 bear in mind that this is only for the box, you will have to supply the HDD separately, either the one in the desktop or buy another one, expect to pay $3000+
If you are planning on taking the HDD from a desktop it is 99.99% certain to be 3.5"
A laptop will most likely be 2.5" or if it is an ultra thin/ultra portable or some other ultra that means you paid more for it because it was the super deluxe small version, it may be 1.8"
Using the HDD from you old system will obviously require using screwdrivers and involve taking things apart. This isn’t something that’s particularly hard to do but if you are going this route because the “Buy a crossover cable” suggestion sounded too hard, you probably need a friend to help.
Transferring 15GB with a USB 1.1 connection will take 3* hours under theoretical ideal conditions, you can expect it to take much** longer. If you are using a new HDD, you will have to do 2 transfer operations, one from the old PC HDD onto the USB HDD, and one from the USB HDD onto the new PC.
If either of the PCs is using Windows 98 you will need to install a driver for the USB box. Some boxes do not include the driver anymore.
The crossover cable suggestion is much cheaper and easier if you are only planning on a one off job. I’ve seen the cables in all the PC stores (3C, Fortress, etc.)
Things to look for:
UTP/CAT5/CAT5e/CAT6 (choose any of these. Note: Paying extra for a CAT6 over CAT5 would be a waste for this job)
Things to avoid:
Patch cable, PC-Hub
Length of cable will not make a difference so select buy price. Expect to pay NT$150.
A thing that might be worth noting is, if one (or both) of the ports on the PCs says anything about “AutoMDIX” (check the manual) you can just buy any cable.
*15GB = 122900Mb
USB 1.1 transfer rate is 12Mbps
122900/12/60/60 = 2.8
USB 2.0 transfer rate is 480Mbps so will obviously be faster but for this to work you need both the port on the PC and the box to be 2.0, otherwise you have to use 1.1.
**I’m talking “leave it overnight”