Depends on how old your video card is, and how fast the new video card is... also you might find your system is processor limited.. if that's the case, your processor could be limiting your preview speed as well.

With Vista, you can do a system evaluation, and my slowest componant that needs updating isn't my ati x1950 pro... it's my main processor.

Your memory speed can also be an issue with new systems as well as hd access speed.

Lots of factors all working together for optimum speed.

Way too many people take way too many things way too seriously.