New Hard Drive detected by system but Windows XP does not recognise it.

After installing a new Hard Drive the CMOS setup sees the Hard Drive correctly so it is connected correctly but in windows after it has been installed by the the Add New Hardware Wizard it is not shown in My Computer.
what is happening here is that windows hasn't created a partition for this drive or it hasn't been initialized.
To verify and correct this we have to go to Disk Management this is done by clicking on Start, click Run, type compmgmt.msc, and then click OK
In the left pane click on Disk Management ,your disks and partitions are shown.
To create a new partition, right-click the unallocated space on the disk where you want to create the partition, and then click New Partition ,when asked choose Extended Partition(primary is more for installing an operating system and booting of it) ,choose the default size ,when done click Finish(or close).
For an Extended Partition we need to create a Logical Drive so right-click your new Partition and choose create Logical Drive follow the steps and at the end you have the option to Format it ,do it so that Windows will see your drive .
when complete close disk Management and see if the drive is seen In My Computer.
Here is more info if you get lost;
http://support.microsoft.com/kb/309000/en-us