Video Upgrade (Duel Monitor Display)

I have a client who has a Dell Dimension DXP061 with a Nvidia GeForce 7300 LE. He recently bought two flat screens and want’s to use the duel monitors. The problem is the 7300 don’t support that so I was wanting any advice in getting a new PCI-E Video card that would support this and actually run in his system. I am unsure (But guessing) that this PC isn’t PCIE-2.0 (Although the current card is PCI-E) and were looking for a cheap Nvidia Solution. Any advice would be greatly appreciated.