Video Editing programs like Adobe Premier Pro, Sony Vegas Pro and Sony Movie Studio Platinum, now utilize both your CPU and Graphics Card to improve performance.
Both help to process live playback in the preview window and for the rendering of your project videos. However, there is more to the story than just your CPU (Central Processing Unit) and GPU (Graphics Processing Unit / Graphics Card).
Many other components that are part of your computer, can also have a siginificant effect in the peformance you get out of your video editing software and other related special effects programs, that go hand in hand with video production.
Technology is continually changing at such a rapid pace, that some parts of this article may become obsolete in the coming years. However, the core theory that I am about to discuss should remain solid for quite some time.
Thus having a computer with a fast CPU, is a Number One priority for anybody who uses Vegas.
The best CPU chips to look out for are the brand new 2nd Generation "Sandybridge" Intels: #1 Intel i7 2600k, #2 Intel i5 2500k, #3 Intel i7 2600, #4 Intel i5 2500. The next best level would be the first generation i7's and i5"s.
In the AMD range, the best chips for Video Editing are in the Phenom II x6 core series: (#1) 1100T, (#2) 1090T, (#3) 1050T. Next level down is Phenom II x4 core series: 975, 970 or 965.
A fast CPU, also means that you need plenty of RAM to support it. 4GB's is the minimum you should have, but 8GB's would make more sense to match a high end CPU chip. Please remember though that 32 bit Operating Systems can only use a maximum of 4GB's of RAM. You need to be running a 64 bit OS, if you plan on having MORE than 4GB's of RAM. If you go into any computer store today or check online, you will notice that 64 bit Windows Operating Systems are becoming the norm now. If you are building or buying a new computer, there really is only one choice for an Operating System at the moment - Windows 7 64bit.
Graphics Cards - GPU
Getting back to GPU's (Graphics Processing Units) and Vegas. Vegas does have one function that will take advantage of a GPU - rendering Sony AVC Video files - thats it! Anything else that you want to render will be processed through your CPU. There is another catch as well. Vegas can only use NVIDIA Graphics Cards, not ATI Radeon.
NVIDIA uses a unique system called CUDA blocks. CUDA blocks can split a task up into many "blocks" and process them simultaneously, thus speeding up rendering times.
From all the forums that I searched, it appears that NVIDIA CPU rendering only speeds things up by about 30%.
So after all that, I really don't know if it is worth while getting an NVIDIA GPU, specifically for Vegas in your new computer system. ATI cards are extremely popular with gamers. Having a good graphics card is still very important for your whole system if you want smooth playback of High Definition Video on your Widescreen Monitor.
Another VERY important part of a system designed for Video Editing, is storage. You need a FAST Hard Drive and more than one. The optimal configuration is to put your Operating System and Vegas on a dedicated #1 Hard Drive and have all your Media files (video, music, pictures, etc) on a #2 large separate Hard Drive. If you were really "in to it", you could even go for TWO media Hard Drives to split things up even further. Having separate hard drives splits up the work so that reading and writing of files does not bottleneck and thus defeating the purpose of having a fast CPU. SSD (Solid State Drives) are now here and would make an excellent choice / replacement for your Number One drive - no moving parts - lightning fast boot up times. You will have to pay for it though. When choosing Hard Drives, make sure they are fast - running at 7200rpm. Hard Drives are as cheap as chips now, and it doesn't cost much to get this part of the system right.
Links to Excellent Articles and Resources
Here is a link to an EXCELLENT online article that talks in-depth about what to look out for when building or buying a new system for video editing.
Here is a link to a Review of the NEW Intel CPU's, that shows the differences between the different brands and models of chips.
Here are some links to 4 of the Best YouTube Channels that are experts in Computer Hardware Reviews and Technical Information on building your own computer system.