I would appreciate some advice on a good mobo for a photo editing workstation. The most demanding applications I use are Nikon Capture NX for RAW photo conversion, Photoshop CS3 for other photo editing tasks and other photo editing software. During the editing process, the files can be as large as 200 to 500 MB and require a fair amount of processing power and memory.

I need a generous number of fast USB connections for printers, scanners, cameras, external HDs for storage, etc.

I am inclined to go with a Vista 64-bit system using an Intel Quad Core processor and 4 GB RAM to maximize present performance and to "future-proof" the system for a couple of years.

Please note that I have no interest in gaming or use of multiple monitors.

Any advice on a good mobo would be much appreciated. (If you have advice for a graphics card, that would also be appreciated.)

Asus P5K-E or Gigabyte GA-P35-DS4. They got RAID on board (it'll help you on conversion).
For USB, Asus got 10 ports and Gigabyte got 8. I think they will cover your needs.
For external storage, Asus has 2 ports of e-sata.

First of all Motherboard isnt important for Photo editing, the main thing which is important for video editing, photoshop and .... is the CPU and RAM
QuadCore + 4GB RAM (which u mentioned) is a very good combo

and for a motherboard go for a P35 board like
ASUS P5K or GIGABYTE P35 DS3L

Slicessoul, Maziar: Thanks very much.

No problem mate glad i could help u