Hi
Subramanya here

I am able play video cd using Xine, even though it ha .dat format.But i am not able to play the file from the memory (Hard Disk).Any body please help.

VCDs have dat files on them - as far as I know - is this a VCD you are trying to copy and play?

there are two ways I know of how to achieve what you are trying:

there is a tool called vcdimager (or similar) which will copy the whole VCD and not just the dat files

mplayer can play VCDs - and if it can play them it can also dump them to your disk.

to play it:
mplayer vcd://1

to dump it:
mplayer vcd://1 -dumpstream -dumpfile ...

this should work - I don't have VCDs but this worked with every format I ever had - I use it to dump DVDs to disk