how to delete HD partitions screwed up by DOS' fdisk

[Hector Akamine <akamine@example.com>]

Somebody in the list told me not to use MS-DOS' fdisk, but ........ 

My PC's hard disk (30GB) had 4 partitions, and used to dual-boot (until
fdisk screwed it) between win2000 and linux

DOS' fdisk reported:

1 (active) NTFS
2 Non-DOS
3 Non-DOS
4 EXT DOS

LINUX's fdisk reported:
                     ID   system
1 /dev/hda1   7    HPFS/NTFS
2 /dev/hda2   83  linux
3 /dev/hda3   82  linux swap 
4 /dev/hda4    f    win95 extended (LBA)
5 /dev/hda5   83  linux
6 /dev/hda6   7   HPFS/NTFS

hda5 and 6 are logical drives in the extended partition (or at least I
suppose that)

I wanted to delete all the partitions, create new ones and install again
everything from scratch, then I ran DOS fdisk to delete the partitions:

First fdisk asked me if I wanted support for large disks and I answered
"Y". It showed me the 4 partitions, but it didn't show me the ones
inside the extended partition. When I wanted to delete the extended
partition it refused because it said there were logical partitions, but
it didn't showed me them (it said there were none defined). Then I
switched to linux's fdisk to try to delete from linux, but .......

now win2000 doesn't boot (it freezes during start-up when it is
"optimizing my system"). Linux boots, but when I run fdisk, it reports
only the first 3 partitions with errors (physical and logical start and
end points don't coincide), and that the partition table entries are not
in disk order.

I just want to delete everything and start from scratch but I don't know
how to delete the partitions since linux's fdisk reports my HD is
screwed up. Any suggestions?

Thanks in advance