Until a year or two ago, I used a Powerbook (laptop) for my office work and a Mac Pro (desktop) for my home computing and photography (Photoshop). Probably like many others!
When the Macbook Pros arrived, I decided that they were more powerful than my previous Mac Pro desktop computer, so I consolidated all of my computing into my Macbook Pro, sold my old Mac Pro, (and almost came out even!) My life instantly became much easier. No more trying to synchronize email and other files between computers (despite the .mac accounts, it's a major pain!)
I always wondered, though, how to optimize my Macbook Pro for Photoshop use, since now and then it seems to slow down. Do I get an external drive to serve as a scratch disk? Do I increase the size of my internal hard drive? And darn, I wish I could put more than 4 gb memory inside!
He then linked his recommendations to the OWC (Other World Computing) website, where all of these items are available for easy purchase on a single page!
p.s.: Lloyd recommends an external e-sata striped drive for a scratch disk, increasing the size of the internal hard drive, and increasing the memory to 6gb (it's now possible, with OWC's new memory!) See his website for details and the link.