Or, if you're like me, and don't have a DVD drive, do what I did (I'm running on a 10v, but the hardware differences shouldn't matter):
1) Clone your Windoze CD to a flash drive by using a PC/Mac with a DVD drive and the appropriate software
2) Start up into OS X on the Mini
3) Open up Disk Utility and partition enough space off of your HD/SSD
for a Windows install. Format as FAT32.
4) Shut down, and stick the cloned XP stick into one of the USB ports. Make sure that USB Legacy support is turned on in the BIOS.
5) Start up from that stick, either by changing the boot order or a one-time boot menu
6) Install Windows on the FAT32 partition. Reformat it, though, to FAT32 or NTFS to prevent any read/write errors later on.
7) It's going to say that it needs to change the active partition. Ignore that, and continue the install.
8) Get Windows configured (post-install setup, drivers, whatnot)
9) If you still have it, start up into your Mac OS X install DVD (or, alternatively, erase the XP stick [or take another stick] and install a bootloader so you can access your existing install, not recommended)
10) Go into Terminal and type in (without the quotes): "diskutil list". Note which drive your OS X install is on (it should be something like disk0s2).
11) Type in (once again without the quotes) "fdisk -e /dev/rdisk0" (substitute the 0 with your drive number, which is the 0 in disk0s2)
12) Ignore the error that comes up about not being able to load the MBR, and type "p" into the prompt. It should reprint the drive list, albeit in a much different format than the diskutil command did.
13) Confirm the second number of your OS X partition (the 2 in disk0s2, in my example that I've been using) and type "f 2". Hit Enter, and it should say it sucessfully set the OS X partition as active. NOTE: Substitute your second number for the 2 in my example).
14) Type in "write", so it saves the changes to the bootsector, and type in exit twice (once to exit fdisk, twice to exit the Terminal session)
15) Done! The netbook will be able to boot into either OS X or Windows from your bootloader of choice (I use Chameleon RC2)
EDIT: Duh! I just realized this is for a dual-boot config. If you want it to convert all the way back to Windows, a 100% reinstall, complete steps 1, 4, and 5, and completely reformat the "Unknown Partition" in the XP installer.