If you use the method of just having one central wallet for 3 addresses the easiest way to identify what you've receive for each individual address is to search for that address in the block explorer. On thinking further about this it may be more simple to have a separate wallet on each machine but the choice is what you find most convenient really and whether you want to use the disk-space on each of your machines for the blockchain.
According to the Litecoin hardware comparison page at
https://litecoin.info/Mining_hardware_comparison the fastest AMD laptop GPUs seem to be the AMD 6990M and AMD 7970M . I'd be verrry reticent to advise GPU mining on a laptop though. From what I've read you'll be likely to have big problems with heat and could possibly fry your machine.
Thanks a lot dear for all your help , very gracious of you , I will see whether to go with a CPU or buy a GPU for my laptop , it all depends on my next salary . So as of now I will stick on to CPUMining , any suggestion for a good GPU for a tower or CPU unit.