PS6 is
starting to introduce graphic acceleration for images, but everything before that (including Lightroom) only uses 2D OpenGL for zooming, panning and rotating images. It doesn't matter what graphics card you have as long as it is current and does basic OpenGL. I've tested it on a 9600GT, 450GT in my 2600K desktop and noticed no difference, I've also tested it on a 525 and i7-integrated graphics on a laptop and it is fine. Certainly very, very usable (and I work with Canon 5D2 raw images that are 21Mpix in size).
Looking at the PS faq for CS6 (
http://helpx.adobe.com/photoshop/kb/photoshop-cs6-gpu-faq.html) it introduces the following graphics accelerations:
Those are what I'd call graphic design functions - I certainly don't use them much for photography. I'd wait for CS7 before I'd worry about a fast graphics card unless I made use of the above a lot.
Always assuming the OP is using Photoshop products of course
This will depend on your usage model. Lightroom 4 is limited in the memory it uses (I've never got it to go above 2G on an x64 install). PS is more memory hungry, but if you only have a few images open at any one time, the 8-16G will mostly be sat used as a disk cache and not in real use. I would agree it is better to spend £40 on memory over an extra £40 on graphics cards
There are very few operations that take any length of time in Photoshop given the speed of todays machines. When I've benchmarked my PS installation in both 4 core (BIOS disable hyperthreading) or 8 core mode I get 10-15% better performance on the (heavily automated) benchmarks. In real life, where the CPU is spending most of the time waiting for your input, your workflow is unlikely to be any faster with an i7. It's another £70 to spend elsewhere (like on a decent IPS monitor hint hint
)
![[WU-TANG]GZA](/styles/overclockers/avatars/4.png){kind=avatar}
