I'm having trouble installing Ubuntu in my Dell Inspiron 630m.

I inherited this laptop, and it was full of evil, evil software. So, immediately upon getting it, I installed Natty Narwhal. For a whole week, I've been successfully dual-booting Ubuntu 11.04 and Windows XP as I cleaned the computer up--no problemo. But yesterday, I decided to do a fresh install of Windows XP Pro, and that's when everything went wrong. XP now works fine, but as is the wont of Windows, it blew Linux away. When I go to re-install Linux, the live CD does not recognize any partitions on the harddrive at all; in fact, it seems to think that the entire harddrive is unformatted. The same goes for GParted.


I've looked at previous posts regarding partition problems upon install, but I can't find any solutions that really fit the bill. I've defragmented my Windows partition to no avail, and fdisk knows that the partitions are there (see the output below). When reading the fdisk output, it looks to me like I have a corrupted partition table, which I would have no clue how to fix. Any help here would be much appreciated--anything, anything that might save me from the horror of primarily proprietary bootage

Code:
ubuntu@ubuntu:~$ sudo fdisk -lu
omitting empty partition (5)

Disk /dev/sda: 78.7 GB, 78732380160 bytes
255 heads, 63 sectors/track, 9572 cylinders, total 153774180 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x41ab2316

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *          63   128262959    64131448+   7  HPFS/NTFS
/dev/sda2       128278526   153772031    12746753    5  Extended
/dev/sda3       149600256   153772031     2085888   82  Linux swap / Solaris
/dev/sda5       128278528   145424383     8572928   83  Linux
/dev/sda6       145426432   149598207     2085888   82  Linux swap / Solaris

Disk /dev/sdb: 1048 MB, 1048051712 bytes
33 heads, 61 sectors/track, 1016 cylinders, total 2046976 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x6f20736b

This doesn't look like a partition table
Probably you selected the wrong device.

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   ?   778135908  1919645538   570754815+  72  Unknown
Partition 1 has different physical/logical beginnings (non-Linux?):
     phys=(357, 116, 40) logical=(386555, 11, 23)
Partition 1 has different physical/logical endings:
     phys=(357, 32, 45) logical=(953624, 6, 61)
Partition 1 does not end on cylinder boundary.
/dev/sdb2   ?   168689522  2104717761   968014120   65  Novell Netware 386
Partition 2 has different physical/logical beginnings (non-Linux?):
     phys=(288, 115, 43) logical=(83800, 2, 1)
Partition 2 has different physical/logical endings:
     phys=(367, 114, 50) logical=(1045562, 23, 53)
Partition 2 does not end on cylinder boundary.
/dev/sdb3   ?  1869881465  3805909656   968014096   79  Unknown
Partition 3 has different physical/logical beginnings (non-Linux?):
     phys=(366, 32, 33) logical=(928902, 28, 32)
Partition 3 has different physical/logical endings:
     phys=(357, 32, 43) logical=(1890665, 16, 36)
Partition 3 does not end on cylinder boundary.
/dev/sdb4   ?           0  3637226495  1818613248    d  Unknown
Partition 4 has different physical/logical beginnings (non-Linux?):
     phys=(372, 97, 50) logical=(0, 0, 1)
Partition 4 has different physical/logical endings:
     phys=(0, 10, 0) logical=(1806868, 19, 53)
Partition 4 does not end on cylinder boundary.

Partition table entries are not in disk order