"new to advanced computing" or not, you are very brave to dive strait in to the deep end, as most novices will dual boot for a while. Good on you!
In any event, if we assume here that your XP partition is the first one then it will be called /dev/hda1 under linux. To be sure we can use the fdisk program to dump your partition table. Here is sample run from my system:
[me@mine]# fdisk -l /dev/hda
Disk /dev/hda: 200.0 GB, 200049647616 bytes
255 heads, 63 sectors/track, 24321 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/hda1 * 1 7 56196 83 Linux
/dev/hda2 8 1224 9775552+ 83 Linux
/dev/hda3 1225 3657 19543072+ 83 Linux
/dev/hda4 3658 24321 165983580 5 Extended
/dev/hda5 3658 5482 14659281 83 Linux
/dev/hda6 5483 5544 497983+ 83 Linux
/dev/hda7 5545 6152 4883728+ 83 Linux
/dev/hda8 6153 6760 4883728+ 83 Linux
/dev/hda9 6761 7369 4891761 83 Linux
/dev/hda10 7370 7978 4891761 83 Linux
In my case I have no windows partitions, but you will be able to pick it out as it will not have "Linux" under the system column. Having identified which partition, we can now reformat it using fdisk, or if the interface is too cryptic some prefer cfdisk, which is the same basic app but more user friendly.
Now, here is where I don't remember (please chime in someone if you know) but you either have to delete the partition, then create a new one in the same spot, or perhaps you can simply change the partition's system id (to 83/Linux) then write a new Linux filesystem to it.
Now you must decide where you want to mount the new empty filesystem/partition. For example, you may want to have your /home directories on a separate partition, so you would need to backup and archive whatever is currently on your /home (using tar) so you may do something like:
# mv /home /home.bak
# tar czf home.tar.gz home.bak/
Now you mount your new partition at /home and untar your backed up home directory. Now your /home is separate rather than being a part of '/'. You can of course pick a different directory mountpoint if you wish.
Anyway, that is a lot for you to digest, and I am sure you will not understand it all on first pass. That is OK. I suggest starting with 'man fdisk' to see how that program works.
Also, I can not recommend enough that you pick yourself up a good beginnijng Linux book to help out with the thousands of questions you will surely have. My pick would be "Running Linux" by Matt Welsh et al. This is the book I cut me teeth on...
If you cannot or don't want to get a dead tree book then there are also tonnes of documentation on the web. Try:
(good, though a bit dated)
Above all, use LQ.org for any question/concerns you cannot address elsewhere. If you have some more specific questions about the points I have brought up feel free to ask away, as there are many people ready to help here...
PS: found this on the site: might help with background on how Linux partitions work, and how to use fdisk: