I was thinking of getting a video card that supports Vegas. What shuold I look for or take note in terms of Brand, Specs such as processing speed, ram etc. Thanks!
Any card will support Vegas as it doesn't make use of it. I suggest a card that supports 2 DVI outputs so you can run dual monitors. It is the only way to go! I don't know what system you have so it is hard to say what card you can run. I have a nVidia 8800GT 512mb super clocked. I am very happy with it but you need a machine and power supply that can drive it.
I'm getting along very nicely with 2 x Gigabyte Geforce 8600GT with 2 x DVI on each. I've got 2 x 17" LCD on one and a 24" Dell on the other for my Vegas video preview.
I'm seriously thinking of adding a 4th monitor such as a 22" wide one.
A very good and cheep solution is Blackmagixs Intensity or Intensity Pro - since the preview capability are really great - via HDMI out, and an HDTV you get a much better HD preview picture, compared with grafic cards that I have tested, like the MSI RX2600RT.
Take care, that will not work for a all PC-monitors, the HDMI output form the Intensity is either 50i or 60i. So the use of an HDTV makes here sense.
The Intensity Pro offers then also some analog interfaces - for example also SVHS or component, if you need such an output.