You can buy a swich box that connects 2 computers 2 one monitor.
here is the basic way of doing it.
Instructions
STEP 1: Buy a switch box. Use a search engine like Google or Yahoo to find to switch-box manufacturers.
here is a link to show u what it would lok like
http://www.amazon.co...h/dp/B000J249JCSTEP 2: Buy a pair of SVGA cables if they aren't included with the switch box you buy (kits including a box and cables are a more practical value for most setups).
STEP 3: Buy any necessary adapters if you plan to connect a PC and a Mac to one monitor.
STEP 4: Shut down both computers.
STEP 5: Connect the monitor to the switch box (probably to the center socket on most boxes).
STEP 6: Connect both computers to the switch box.
STEP 7: Tighten all hand-screws on monitor plugs.
STEP 8: Turn on monitor.
STEP 9: Reboot both computers.
STEP 10: Turn the switch box from A to B (or whatever designation the box uses) to make your different computers appear on the monitor.
Useing one monitor through the tower from you'r laptop wont b too good if possible cause of transfer speed and the computer the game is running on gives it the graphics definition. So you dont benefit at all even loose from the quality.