Dual Monitors

hi, i'm trying to do either one of two things, both of which have the same end problem, i want to do dual monitor on my win 7 desktop, so, i have two choices, a regular (and outdated) monitor, or a new win vista laptop. I'm trying to get the pc to recognize one or both secondary monitors, and it will for a second, then beeps, flashes the screen, and says there's only one, beeps again, flashes, says there's two, repeats.

I don't know if it's the software or the hardware but it DOES see them but then says it doesn't, so i dunno. any ideas?

"One or both secondary monitors" ?

Vista laptop as a second monitor?

How many actual monitors do you have? Not including the one on the laptop.

If the laptop has a video IN port, what type is it?

the laptop can take (dunno wat its called) the round headed cord sometimes it's gold, it has 4 prongs and a dash type thingy, but the pc can't, it has two places for a monitor cord, one is for a cord with 12 prongs, not sure how many the other has, i think 15 prongs. sorry if i'm not much help lol, i'm hardware illiterate, my forte is software.