Hello..
I want to know that can Arduino convert Serial Data to Parallel, if yes then to how much bits arduino can convert serial data to parallel..?
Thanks.
thanx brother for posting this question....
i also want to know about this ? 
yes it can.
Serial data (rs232) comes in with one byte at the time = 8 bits. So it can set 8 digital IO lines.
If you collect 2 bytes from serial, you can (in theory) set 16 digital IO lines.
Check - Arduino Reference - Arduino Reference - for optimal performance
With a MEGA you can set even more parallel lines.
Warning note: not all lines are set at the very same moment when using more than 1 byte. Timespan can be very short (micros), but there is a delta T.
Thanks robtillaart.. i hope it will help me..
What is the goal of your project?
Basically I have a CNG FUEL PUMP in which there is a single wire of Data, and a single clock signal which gives a complete answer of a calculation on LCD that how much Gas you have put in a Car, which means a single wire of Data is a serial Data, and i have given that single wire that make your own display for that calculation. So i want to convert that serial data to parallel data (using Arduino as i have it) as i'm not getting any idea from serial data so i can get some idea from parallel data, that what to do next?