The best way is to Fdisk and Format. This is what I use;

If you don't have a Boot Disk, you can make one, go to "Start" - "Settings" - "Control Panel" & select "Add/Remove Programs", select the "Startup Disk" tab, follow the instructions.
NOTE: Dos Command number to use is in Brackets ( ), Boot Disk must be in A: drive at all times.
To get into FDisk, just type "FDisk" (without the quotes) at the A: prompt, if you're asked "Do you wish to enable large Disk Support", answer yes, this will make your HDD "Fat 32"
Warning Aways make sure you have made a copy of all the important data you have made(documents, pictures etc), FDisk will completely erase all data on your Hard-Drive
Deleting Partitions
If your drive is one partition, only do steps 1, 4 & 5
1. ( 3 ) Delete Partition or Logical Dos Drive
2. ( 3 ) Delete Logical Dos Drives in the Extended Dos Partition
3. ( 2 ) Delete Extended Dos Partition
4. ( 1 ) Delete Primary Dos Partition
5. Esc your way out & re-boot the machine
Creating Partitions
1. ( 1 ) Create Dos Partition or Logical Dos Drive
2. ( 1 ) Creat Primary Dos Partition
3. Choose No to the next question if you want to create extra partitions & go to step 4, if you don't want extra partitions go to step 9
4. Choose size (in MB's or %) you want C:\ drive to be, enter when done
5. Esc
6. ( 1 ) Create Dos Partition or Logical Dos Drive
7. ( 2 ) Create Extended Dos Partition ( just hit enter for the default number shown, you get to enter the size/s for your extra partitions in the next step)
8. Choose size (in MB's or %) you want each partition you want, ie: D:\ E:\ F:\ etc
9. Esc
10. ( 2 ) Set Active Partition
11. Choose Partition 1
12. Esc your way out & re-boot the machine, then Format each new partition you have created, you do this by typing "Format" drive letter : eg: prompt format C: (with a space between the Format command & the drive letter)