Integrated means built into the motherboard (which may have dedicated memory, or it could take a portion of the main system RAM). Laptops generally have integrated graphics. With a desktop, if the graphics are integrated the video cable connector is usually oriented vertically, along with the ethernet port, possibly audio jacks, usually a couple UBS potrs, etc. Discrete graphics (a card you can pull out and replace), would usually have the port lower down the back of the case, oriented horizontally.
If you run dxdiag, it can generate a report detailing some system information, and should probably indicate whether the graphics are discrete or integrated. Vista moved some stuff around compared to XP; I think you should be able to run dxdiag by clicking Start, browse through All Programs / Accessories and click on Run (or hit the WindowsKey+R), type in dxdiag and hit Enter.
