So can I Install 64 bit O's Either (Windows 7 or Linux )on it ,Does it works well with performance ? Does 64bit O's (Windows 7 or Linux ) supports my 4Gb ddr2 Ram N utilize full memory ? Thanks in advance

If it's a Core 2 based system then it will support a 64 Bit OS.

Yes yes and yes you can install 64 bit OS (Linux, Windows or anything you can install :)) on your laptop. It will use the 4 gig RAM. 64 bit OS can use all the RAM you present to it.

Can you give us a model number so we can get a better idea of what your using ?

Dual core has been around for some time and not all dual cores are 64 bit. Please let us know.