How to delete all partitions for a complete reinstall

[Kevin Zhao]

Hello,

I am now using dual boot windows xp and ubuntu dapper. The problem is
my partition table is a bit messed up, although ubuntu is so far so
good. Now my OEM recovery CDs(laptop) refuse to work due to partition
problems and I wish to delete all the partitions to make a clean
environment for a reinstall. I wonder which commands (fdisk -xxx? etc)
can be used if i boot using ubuntu live cd.

Oh and i hope it can be tender to my harddisk. Thank you in advance.

Regards,
Kevin