I got a seagate 300gb hard disk which I installed with no problem until I try to store more than 80gig of data. It simply refuse to accept the additional data.  
 
I am using xp with sp2. The window xp shows 300gig of hard disk but the bios only shows 80+++gig of my new hard disk.  
 
So I update my bios successfully and now my bios shows my hard disk actual 300gig size.  
 
But my new 300 gig still refuse to store more than 80+++gig of data.
 
Please help

You probably partitioned it to 80gb when installing windows with it, meaning you could simply right click on "my computer" then choose "manage" find the disk management, and make a new partition.

no my 300gb hard disk is set as slave as a logical drive. I created only a single partition using ALL the hard disk space. Capacity is 298.08gb and free space 212.61gb (71%) free.

Just how old is your motherboard?
The usual; try it out in another computer.
If that fails, or you can't;
Try simply remaking the partition and formatting slowly.
Will take forever, but indicates hardware error if it fails.
 
Personally I've had absolutely hideous experiences with Seagate, they break. All the time

You might have the jumper wrong. Sounds like you jumped it to be 80G only. Check the jumpers again.
 
If not use disk management to recover the rest.

I agree, sounds like a jumper problem, although with SATA HDD's there are no jumpers, its based on which SATA port on the mobo.  Anyway, I would check the jumpers on the drive, it could be set to limit the drive to 80GB or less.  If thats not the case, then I would think using disk management would be a good idea.  Check the partitions of the drive.  
 
my 2cents.

 
they do have jumpers...

its an IDE hard disk

Backup the data on the disk, reformat the drive and restore the data. It sounds like your partition table is corrupt.

yes you guys are right. I have set the jumpers and connections wrongly. Thanks very much. But why the 80gig++ limitation?

limitations: some older mobos can't handle LBA (Logical Block Addressing) addresses bigger that a certain size in BIOS. In order to use the disk in these older systems, jumpers are used to artificially reduce the LBA reported by the disk.
A disk block is typically 512 bytes, making 80 Gb equal to around 160 billion blocks. It is also probably the size of a drive platter (4 platters of 80 Gb), and under 2^38 (max LBA accepted by some older boards) blocks - the jumper probably disables access to 3 platters to implement the solution.
In such a case, you can (after resetting the jumpers correctly):
 - reformat the whole disk (lousy, gotta reinstall OS)
 - create a second partition that you will use to store your data (allows easy OS reinstall, faster defragmentation, no need to reinstall/reboot, zero risk)
 - use a Linux LiveCD to resize the existing partition to take up the whole disk (works wonders with NTFS, yes sir)