The partitioning step should be the only thing you have to do manually, the rest should be done through a script and you can just select the default options.
I'm not sure if you realise that DSL can actually boot from the CD, so you run the OS from that to use during the installation. Once it has loaded the desktop, open a root terminal window (in the DSL menu this is under "Xshells>Root Access").
Now type the following and press "enter":
cfdisk -z /dev/hda
This should bring up an interface showing one partition entry labeled with the type "Free Space".
Now use the left/right arrow keys to select the "new" button at the bottom of the window and press "enter". Then press "enter" at the next two prompts ("primary" and the partition size) as the default values will do.
Finally press "enter" on the "bootable" button (selected after the previous steps), then move to the "write" button and press "enter", then confirm that you want to make the changes (this step will destroy the Windows installation).
If you make a mistake, just go to "Quit" and start again, nothing is changed on the HDD untill you tell the program to "Write".
We didn't make a swap partition for the PC to use if it runs out of memory because your machine has more than enough to run DSL very well without using the HDD for extra.
Now it's hard to know whether you would want a Frugal or HDD install, but a HDD install would make it easier to install new software and keep settings changes, so I'll describe the process for that:
Open the DSL menu and go to "Apps>Tools>Install to Hard Drive". Type "hda1" at the first prompt and you should be able to press "enter" at the following options to use the default values.
When it's done, restart the computer and remove the DSL CD before it starts booting. You should boot to a menu of boot options (the default one is best for starters), then when you press "enter" DSL should start booting and you'll be set.
However before you do the above, I do recommend that you first have a play with DSL running from the CD to see that it works properly and does what you want. In particular the version of "Firefox" web browser it comes with, and which can't be upgraded, is old and incompatible with a few modern websites. A more modern and perhaps easier to use Distro that may work with your hardware is Knoppix (http://www.knopper.net), it still requires you to manually create partitions though (including a swap partition).