Alright...here we go
using fdisk you can make a primary partition of any size you wish. Then you have to make a extended dos partition if you want to add more drives because you can make only one primary drive using fdisk. If you are planning to keep only drive for you win xp the forget about the extended drive anyway. There are many good Linux distros around ...you can try Red HAt 8.0 or Mandrake 9 or something ...then boot from the linux cd rom and follow the instructions upto the partitioning and setting the root stuff. Use disk druid...fdisk or anything which you may feel easier and make the partions acoordingly. Then proceed with the installation.