Always check the motherboard's website for CPU compatability. I personally only buy RAM that has been tested and approved by the motherboard manufacturer, less chance for issues that way. For the best performance with modern graphics make sure your motherboard supports PCI-E x16, 2 of them if you want to crossfire or SLI in the future!
Also, most modern motherboards support only SATA and have done away with IDE for hard drives, so be aware of that, though for most it isn't an issue. Also, I believe AMD and nVidia both have a utility available to determine which powersupply is best for your build based on graphics cards.