Backup/Rescue CD Set
The preinstalled WinXP on most modern Thinkpads comes with a software to create rescue discs. It can be found in the "Access IBM" section of the Windows menu. I recommend to create a set of rescue discs before you repartition the drive. When you create the rescue discs, use a CD-R for the first volume (it's only 280 Megs) and then DVD-R. Otherwise you will end up with seven CD-Rs.
If you intend to sell your Windows it is also recommendable to remove the license sticker at the bottom of your Laptop as soon as possible because it goes off a lot easier right after your purchase. But take care, M$ invested quite some energy in making the sticker rip and tear when you try to remove it.