HDD not detected after ubuntu installation

[Megatronix]

I have migrated from vista to Ubuntu.
I had installed vista on a 250GB HDD, and I connected another 80GB HDD and installed ubuntu on it.
During installation my other 250GB HDD was detected. But after installation, the HDD which had vista installed is not being shown. I don't need vista but I have important files on it and I need them urgently. What do I have to do to access it?

[devils casper]

You have to mount partitions of Vista HD.
Open Terminal and execute this

sudo fdisk -l

Post output here.

* Its small L in fdisk -l.

[Megatronix]

after executing the command, this is what I got:

deepak@optimusprime-machine:~$ fdisk -l
Cannot open /dev/sda
Cannot open /dev/sdb

[devils casper]

You must use sudo to gain root privileges.

sudo fdisk -l

[Megatronix]

This is what I got when I used sudo:

deepak@optimusprime-machine:~$ sudo fdisk -l
[sudo] password for deepak:

Disk /dev/sda: 80.0 GB, 80026361856 bytes
255 heads, 63 sectors/track, 9729 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0xb330b330

Device Boot Start End Blocks Id System
/dev/sda1 1 246 1975963+ 82 Linux swap / Solaris
/dev/sda2 * 247 9729 76172197+ 83 Linux

Disk /dev/sdb: 250.0 GB, 250059350016 bytes
36 heads, 5 sectors/track, 2713317 cylinders
Units = cylinders of 180 * 512 = 92160 bytes
Disk identifier: 0xa9b0c4f9

Device Boot Start End Blocks Id System
/dev/sdb1 * 12 2713305 244196352 7 HPFS/NTFS

Disk /dev/sdc: 4055 MB, 4055890944 bytes
33 heads, 63 sectors/track, 3810 cylinders
Units = cylinders of 2079 * 512 = 1064448 bytes
Disk identifier: 0x00000000

Device Boot Start End Blocks Id System
/dev/sdc1 1 3811 3960815 b W95 FAT32

[Megatronix]

This time, when I rebooted my pc, the 250GB hdd was detected.
When I tried to access it, it asked for the vista admin password since I had vista installed on it. Though I could access the hdd, the contents arent visible and I get the following error message:

Unable to mount location
Internal error: No mount object for mounted volume

[devils casper]

Execute this

sudo mkdir /media/sdb1
sudo mount -t ntfs-3g  /dev/sdb1  /media/sdb1  -o defaults,umask=0
ls /media/sdb1

[Megatronix]

I executed the commands and it helped me easily mount the volume.
But when I checked for the contents all that I found was this

$bootdrive$ boot.ini $lsdrive$ NTDETECT.COM ntldr $WINDOWS.~LS

What about the other files that were there on the hdd?

[Megatronix]

And there is one more thing you should probably know:
If I keep this 250GB hdd connected and boot the system, even ubuntu which is installed on the 80GB hdd fails to boot. And I see the following screen:

AMBIOS(C) 2005 American Megatrends, Inc.
BIOS Date: 04/29/05 17:55:16 Ver: 08.00.10
Copyright 2005 by Hewlett-Packard Company
CPU: Intel(R) Pentium(R) 4 CPU 3.06GHz
Speed: 3.06 GHz

Press F1 to run Setup
Press ESC for BBS POPUP menu
Checking NVRAM..
Initializing USB Controllers.. Done.
1272MB OK
USB Device(s): 1 Storage Device
Auto-Detecting First Channel Device 0.. IDE Hard Disk
Auto-Detecting First Channel Device 1.. IDE Hard Disk
Auto-Detecting Third Channel Device 0.. IDE Hard Disk
First Channel Device 0: ST380013AS 3.43
Ultrta DMA Mode-5, S.M.A.R.T. Capable and Status OK
First Channel Device 0: ST380013AS 3.AAC
Ultrta DMA Mode-5, S.M.A.R.T. Capable and Status OK

So I disconnect the 250GB hdd, boot the system, and get to the OS selection menu, then connect the 250GB hdd and boot into ubuntu.

[devils casper]

Execute mount command again. Execute df -h command after that. Post the output of df -h command here.

sudo mount -t ntfs-3g  /dev/sdb1  /media/sdb1  -o defaults,umask=0
df -h