128mb vs 256mb vram?

Question

Well, our 9 month old 2.0 CD failed for the 3rd time and it's being replaced by the newer 2.16 C2D. We're getting a faster cpu but we're losing some mem on the video card. How much will that affect things (iMovie rendering, games on Bootcamp)?

Answer 1

from TweakGuides.com :
The VRAM Stores the Data
The data entering the graphics card is now stored on the card's own local memory, called Video RAM (VRAM), just two chips of which are circled in red above. These onboard VRAM chips provide a similar service to that of regular system RAM on your motherboard; a temporary storage area designed to help speed up calculations by the Graphics Processing Unit (GPU) - circled in yellow above. Basically as you can see, your graphics card is almost like a miniature PC within itself, with its own CPU (GPU), RAM (VRAM) and motherboard (PCB), and operates in much the same way. VRAM in particular not only serves as storage point for data to be calculated for rendering, it also holds completed images (frames) ready for sending to your monitor - see Step 8 further below for details.
This is the reason why the amount of VRAM is increasingly becoming larger and more important on modern graphics cards. The more information that can be held onboard the graphics card's VRAM, the more quickly the GPU can process data and not have to pause to allow more data to be loaded up into VRAM. For example, games with high resolution textures require more VRAM space. When space runs out in VRAM, existing unused textures have to be switched out and new ones loaded up from your hard drive and/or system RAM into the VRAM. This slight pause which results is commonly referred to as hitching (when data loads into VRAM) or stuttering (when data loads up from the hard drive first), and is most noticeable when you enter new areas or see new objects during a game. Your graphics card literally pauses to wait for new data to be loaded for display before continuing.
Performance Tip: This step highlights the importance of having more VRAM on your graphics card. If running a game on a card with less VRAM, you must lower your texture settings and/or resolution, otherwise you will get more hitching/stuttering as data is constantly swapped into and out of the VRAM. This is particularly true if you have a slower hard drive and less system RAM as well. Note further that cooling the VRAM properly is also essential, as almost all cases of noticeable graphical glitches (also called 'Artifacts'), and many crashes and lockups, are due to overheating VRAM. Remember that the temperature sensor on your graphics card is not located on the VRAM - it is on or close to the GPU; so your VRAM can often run much hotter.