The ram doesnt matter - I've installed on systems with 8gig and 4gig and neither were a problem.
Unfortunately I can't help you regarding a graphics card recommendation as I have only tested with three different cards (5870, 6870 and 6970 the later of which isn't working yet) so would basically be guessing. Hopefully the other forum users will be able to recommend a card for you.
I think if I were intending to do video and photography work I would probably avoid the 6000 series ATI cards for now until the drivers mature and instead go for something from the 5000 series like perhaps a 5770 which should work fine using the graphics enabler with no need for the new ati kext files (it should work with the standard kexts from 10.6.5 upwards).
I've planned to build a dual boot SL and W7Pro 64-bit based on:
Motherboard: Asus P8P67 Pro
CPU: Intel i7 2600k
PSU: Corsair TX650W
Memory: G.Skill RipJaws 4GB x 2 (F3-12800CL9D-8GBRL)
GPU: Not yet decided. I've wanted to use Apple Cinema Display 27", the questions are:
1. Is it required to get the $250 Apple ATI Radeon HD 5770 to enable full usage of the ACD 27" (high resolution, webcam, speakers, ...), or $150 MSI R5770 Hawk Radeon HD 5770 would be compatible?
2. In any case, will the selected combination of GPU and ACD 27" be fully operational in Windows 7?
3. Will it be better to go with Dell UltraSharp 27" because of multiple inputs?
Thanks for any help and info.