I got a Dell Inspiron 537 ...One day old !! What do I gotta do as far as video boards go ? Thanks Ya'll in advance..
Your Inspiron 537s has a single PCI-E X16 slot. The bad news is that it only supports half-height cards. I think that none of the Radeon 5xxx series, which support more than 2 monitors from a single card, are available in half-height yet.
(Actually, the multiple-monitor feature of the 5000 series may require use of the DisplayPort output. DisplayPort monitors exist, but they're not the norm.)
I expect that the other posters are correct about not being able to run the onboard graphics and an add-on card at the same time, but I'm not certain.
I think you'll need two cards: a PCI-E X16 one, and a PCI one, both low-profile. Win7 is supposed to permit multiple drivers to be installed at once, but I'd probably prefer to stay with a single manufacturer.
Example: the ATI Radeon 4350 is available as a low-profile card in both PCI-E and PCI variants. (
www.newegg.com). You'll be shocked at how expensive the PCI version is, compared to the PCI-E one. I haven't used it, but I suggest it as a low-end card from the latest generation that is available in half-height.
Hanging a bunch of stuff on a small form factor PC like this may not be the best idea, but you may be able to do it if necessary.