So, have the fastest CPU - that's the ultimate. Have the fastest Ram I could find (8-8-8-24). I wanted 6-6-6-18, but couldn't find it. Have the fastest I/O drive technology (SAS), have the fastest SAS drives, and the 2nd fastest SSD. For Photoshop this is PLENTY. It may not be the ultimate games machines, or rendering machine, but then that's not my application, and it only cost 56K.
Got the GTX 285, because in Photoshop they seem to give better performance than other cards. Most cards are made for rendering or gaming. None of the gaming enhancements are going to help the Photoshop experiece.
Tom's hardware has a test where they find that Photoshop with 6Gb is the same speed as with 12Gb of Ram (due to limitation of image size). We will try it and see - maybe we'll put in more Ram.
We make 3D LENTICULAR images. The software that generates the lenticular itself (especially large format), takes 30 minutes on the "ultimate PC" I got 10 years ago (Amd Athlon, 3GB Ram , Win 2K, Ultra 360 SCSI etc). On this machine it takes under 5 minutes, but it's in Photoshop where the real magic happens. The generated files are sometimes right at the edge of the 30,000 x 30,000 pixels barrier, and a simple filter application can take ages - but not on this PC.
I use the SSD for the Windows Swap File and the Photoshop Swap file (2 partitions - one for each file). The SAS drives are running in a Raid 1 config, and completed files are sent to the Raid 6 SAS Nas box.
The 56K is the ultimate - that's the most I've spent on a single PC yet.