What software are you using? Most applications are more geared toward CPU power over GPU power. You need to check if your editing application supports GPGPU. You will need an okay GPU to playback HD video, but nothing close to a 295.
You're probably better off upgrading your CPU to a quad-core than replacing your GPU.
well, in the case of video editing, Quadro is better, it will help take load off the CPU and put it on the GPU through CUDA compatible apps, like adobe premier, and it even helps in photoshop cs3 and i suppose cs4, over all, the quadro will give u better rendering times, it will be faster, but when it comes to playback, the gtx 295 would be better, but u dont need a gtx 295 in sli unless ur gamming, if u still wan tto use ur rig to game and edit, then go for the gtx 295, but if u want it for only video editing, then go for the quadro, that or if u wanted to go with ATI u coudl get the FirePro, its like the ATI version of a quadro, though i take it the quadro might be a bit better, it will cost more
well, if thats the case, well, im not sure if Pinnacle supports CUDA rendering, and so if thats the case, then u don't need a quadro, and u sure don't need a gtx 295, i would say that a 9800 gt would work out just fine because it would be the CPU rendering it, so u would want as good as a CPU as u can get, were if u intend on doing cuda were a program runs on the GPU slightly, then u would want a better GPU, and that's were Quadro is good, but only for rendering videos faster realy, cuz a 295 is also good with CUDA, just not as good, but if u intend on goign for programs in the future that suport the quadro, then get it, if not save the money and get a decent GPU, but u don't need a real high end out, the 9800 GT would be just fine. that and lots of ram, fast ram, DDR3, cuz ram is a good thing for video editing, though if its using the quadro for the rendering, u might not need as much ram, but can't say for sure
ok, so seeing how Pinnacle apparently supports GPU acceleration, then i would say go ahead for the quadro, though u may need to enable something somewere in Pinnacle