Been asked before, but I still need help (dual monitors, PCI)

[NateDog]

Mostly for the computer brains here:

I want to set up dual monitors. My computer is as follows:

eMachines T1096
900 MHZ pentium processor
512 mgb RAM
Running XP home
Congnac+ motherboard
150-watt ATX 1523D powersupply

No AGP slot, but 2 open PCI slots.

What type of card do I need. (Brand names, model #'s would really help).

Will I still be using the original card, or with the PCI have dual heads, and disable the original card?

Am I missing anything?

Thanks,

Nate