This subject has been hotly debated in the Forums and while I realize there is no clear cut answer I want to add from my own experience and possibly help someone who is just getting into photography or someone who has been in it for a while and wants to upgrade their computer. These are my opinions from my experiences and observations and they are just offered as suggestions, nothing more but I think they are certainly valid.
First off you donít have to mortgage your home or drive yourself into bankruptcy in order to have a good computer for photography, there are a lot of great deals out there. If you shop smart $1,000.00 will get a good computer and monitor and will do everything photographically that you needed it to do and last for years.
Forget about a laptop for your primary photography computer. You need the robustness and adaptability of a desktop; a laptop just will not cut it.
For a computer you can do very well with a single core processor and save a bunch of money. Stay away from the Celerons and the Semphrons. They are a joke for anything and for photography anyone who buys one will regret it in a very short time. For an Athlon you can buy an X64 processor in the 3500 to 4500 range and you will do quite well. For a Pentium buy a P4 Hyper threaded processor in the 2.4 to 3.0 Ghz range. Get a large hard drive, either Serial ATA or EIDE. Make sure you have at least 1 Gig of RAM and 2 Gigs if you can afford it. Most computers these days have onboard graphics. Get at least 128 Megs of Onboard video and 256 Megs if you can find a computer that has it. Make sure the computer has plenty of USB 2.0 High Speed ports, 6 to 8 on the back and 2 to 4 on the front. Fire wire isnít anything to worry about so donít mess with it. You should also get an external Backup Hard Drive that connects to the computer via USB 2.0 High Speed but you donít have to get it at the same time you get the computer. You can probably find a computer with this configuration for under $600.00.
For the Operating System the only thing to even consider is Windows XP Professional. Donít even bother thinking of Windows Vista, it is a dog with fleas and the biggest mistake that Microsquish has ever made and you just donít need the headaches.
The monitor is where you really need to spend your money since you will be looking at it day in and day out plus you want a good one so your photos will look incredible. I recommend a Samsung or a Viewsonic monitor. There are many other brands out there but with either of these two you will not go wrong. As far as size is concerned buy a bigger monitor than you think you will need. Widescreen monitors are all the rage but I personally have a Samsung 19 inch 4:3 monitor and it does everything I need. If you want a widescreen (16:9) get a 21 to 24 inch and you will be set for life. If you shop smart you can pick up a widescreen for under $400.00.
Too many people make the mistake of thinking they have to spend lots of money to be adequate and it simply isnít true. Rather than spending $2,000.00 or 3,000.00 on a computer system why not put the difference into good lenses? After all, are we computer operators or photographers? Buy smart and make your money work for you instead of just giving it away. Nuff said!