What are the right cables to use when I want to have 2 screes: One monitor, one laptop?
I've checked out some VGA "Y" cables but they're either too short or the splitted end is female (to plug it in to laptop I need male)

Could I use a DVI-to-VGA  to connect [the tower] to the monitor and use my VGA to connect [the tower] to the laptop?

Laptop monitors are hard wired in to the CPU with a tiny ribbon cable, You cannot directly access a laptops monitor with another computer. The VGA connector on a laptop is an output, not an input. 

You should be able to plug another monitor into the external monitor connection

Then Right Click on the desk top
Select Personalize
Select Display
and follow through to what you want as far as display setup

If it recognizes both the Laptop and the external monitor, it will show up

Yeah, what Mike said.
That's what I do.

Mike 

Could I use a DVI-to-VGA  to connect [the tower] to the monitor and use my VGA to connect [the tower] to the laptop? 


Read his posts , He's trying to use a laptop as a second monitor. 

Cactus Music


Could I use a DVI-to-VGA  to connect [the tower] to the monitor and use my VGA to connect [the tower] to the laptop? 


Read his posts , He's trying to use a laptop as a second monitor. 

Ahhh   I see.   Thanks


Never seen that done


You could almost spend as much in cables and connectors as it is just to go ahead and buy a second monitor for the Tower-thats assuming it would even work connecting the Tower to the Laptop.  Huh?