That system hiro posted would only make sence for a hard core gamer and is over priced for most. 2x $500+ vid cards lol. You dont even need 1 of them to run photoshop at its fastest and could buy a lot better parts the the $1000+ you'll save right there. I suggest a low to middle road vid card. If you dont do gaming or 3d rendering you dont need much of a card at all , youll just waste the money. Grab a Sweet pc monitor or somthing real nice to view and work on your photos with maby?
OCZ Titanium 2GB (2 x 1GB) Dual Channel Kit System Memory
very nice, very fast.
here are the wd's check these out.
http://www.westerndigital.com/en/products/Products.asp?DriveID=65
You hook 2hdd in raid0 Thats standard now on most mother boards. they are sooo fast. When they speed test pc's now that how its done. It effects the whole speed of the pc, I was amazed.
I'd go for the AMD Athlon 64 X2 4800+ 2000MHz HT Socket 939 Dual Core Processor
Get the best motherboard with the best chipset for it. Its worth it, you get the most out of your cpu.
A case.. This case moves air! No it moves air!
I never know a case could make such a difference

very quiet, you just have to see them in action!
after selling so many, and listening how everyone loved them, I had to get one. Great if you wana keep it cool. Rubber mounted anti vibration hdd slide in trays. I love this case :/ Very mature case
http://www.antec.com/us/productDetails.php?ProdID=15139
What about a sound card? Soundbalster live 5.1? Its a nice basic card and great sound.
DVDRW or 2 if you like to double stuff, of course, the fastest out.
You'll need a floppy for the raid also.. lol
This is somthing I'm saving for now... maby next year
http://www.wacom.com/productinfo/intuos.cfm
Anyway good luck, with your new pc