motherboard or graphics card

[#1]

A friend of mine does a bit of video editing.  His computer is a single processor pentium, and he's debating getting a new motherboard to improve the editing.  I wondered, if he could get a similar improvement by installing a graphics card for a similar amount of money, but without the hassle of a Windows rebuild.
My logic is that the graphics card would take the load for the video editing and release his on board memory to improve performance.  Does that sound sensible, or am I just talking nonense (the latter wouldn't be unusual  ;))
If the graphics card idea is a goer, does anyone have a suggestion as to which one?
John

[#2]

It is processing power followed by memory that is the most important factor with video editing due to the real-time and final rendering of the video & sound. So a graphics card will not make much difference unless the on-board graphics is really slow.
So your understanding of what benefits video editing is wrong.
Getting a new mobo with losts of memory and a dual-core processor is the way to go, albeit a much more expensive option.

[#3]

Thanks Peter
Always happy to learn.  I thought (naively) that the graphics card would do the video processing.  I shall now go and beat myself senseless with a wet piece of string in penance. 
In that case, it may just be easier to get a whole new computer, by the time he's got a new mobo, (and lots of memory) and a couple of processors to run it, and probably one or two other bits to make it work, and reinstalled windows for the new bits, and then had to fix what windows broke ... 
John

[#4]

Yeah, graphics card power doesn't influence video processing.  What hardware/video editing software does your friend use?  It's worth noting that not all video editting software can take advantage multi-core CPUs so buying a dual/quad core CPU might not be cost effective.

[#5]

It will still be faster than they currently have.

[#6]

Quote from: Peter

It will still be faster than they currently have.

Yeah, I know that, however many people still believe that two cores are twice as fast as one

[#7]

Of course they are twice as fast - PC World staff say so, so it must be true....
Erm, joke alert! I know that 2 * 1 != 2 when it comes to processor cores