The quad core and RAM would be OK but if you can add RAM for the MOBO do it.
If the CPU is doing a lot of the graphics work (not likely with a quad chip) then you should have a dedicated GPU like Nvidia with on board processing of at least say 1GB of RAM.
If, you are heading into Adobe Premium Professional suite (CS5.5+) for example in video, then Nvidia will be integral to getting maximum levels of cross suite (Dynamic link) uses.
That will use files from within Photo Shop, After Effects, Premiere Pro etc, and link them without reloading each program which bloat the system, and make the changes across the files without being rendered first.
The Mercury playback engine allows for native file edits, without having to transcode when loading video, but, again that will be GPU and MOBO RAM dependent.
If you are NOT using video, then your rig should do just fine with PS, CNX2 etc even at the larger file size.
Even with files converted to TIFF in CNX2 or LR3, my 2 stroke Toshiba, runs fairly fast at files from the D3S, which natively are around 25MB but often exceeding 45MB is size if converted..