Buying a New pc Help Please

Hello People,

About a month back i started up a web design business ( www.bluetigerdesign.com ) and well have you tried running photoshop cs4 on an old pos dell with 512mb of ram? i have and its not the least bit productive. So to cut the long story short i need a new computer. I know il need a good graphics card since cs4 relies more on the graphics card now. So i figured you gamers know all about graphics cards, ram etc, so what specs would be good for photoshop cs4? of course im going to get a custom pc. My budget: $600 us Thanks for your help

if you were meaning to upgrade the dell well you cant cause it doesnt have a pci e card or agp...well i dont know much about pcs so i dont know what cpu to get..