Greetings--- I just purchased a mac pro with the ATI Radeon X1900 XT video card. I plan to run two monitors off of that. I would also like to run a third monitor. -- Is the best (and most frugal) solution to add a NVIDIA GeForce 7300 GT? -- Is this a good idea? -- Will it negatively impact my system's performance at all? -- Is there any significant advantage to adding a second ATI Radeon card, rather than the NVIDIA? Thanks for the help!