VRAM an acronym for Video ram. Generally a term used in computers to describe RAM dedicated to the purpose of displaying bitmap graphics in raster graphics hardware. Video RAM is usually physically separate from the main RAM residing in a computer system. This is not always the case as in some systems the VRAM is shared with the system RAM.
The term VRAM is used more specifically to describe a type of dual-ported ram used in high performance raster graphics hardware. In a raster graphics system, the VRAM is called upon to constantly refresh the display, and at the same time be responsive to modifications from the host system. Dual Ported VRAM can provide data for the refresh system at the same time as allowing accesses from the host to modify data in that VRAM for higher performance.
Using part of main memory for the video display. Shared memory is commonly used in PCs where the display circuitry is integrated onto the motherboard. The disadvantage of shared memory is that it is taking up memory that applications would use, and main memory is normally not as fast as specialized video memory on a stand-alone display adapter. You decide... of course, I would not get the x300... they have much cheaper cards that perform way better than an x300... but, if you have budget, and trust me, I have used an x300se in the past, you can get it, although if you upgrade, say, to an x800, you'll see an amazing difference...