My original plan, which some of your helped me on, for an i5-2500k machine has changed significantly. Looks like most of my budget for a new rig will go towards baby related items so I'm looking for advice on a more value-oriented set up.
My main question is the CPU. Right now I'm deciding between the AMD Phenom II X4 955 Black Edition and the i3-2100.
Initially, the computer will be used for moderate gaming but once the kid comes along I'll be using it as more of a balanced system for video/photo editing, etc.
Do the quad cores of the AMD 955 make enough of a difference in non-gaming functions to pass up the gaming boost provided by the i3-2100?
I would go with the 955, quality, stability, and it's cheap.
Reusing an old PSU always provides some risk, if you want to play it safe I would buy a new one.
Also the 5770 will play many games, but if you want to max out modern games, I would recommend the 6850 or 6870.
I would go with the i3 2100. In all the SB related charts, the i3 2100 performs better (in games and some benches) than even the Phenom II x6 1090T. When it comes to heavily multi-threaded applications, the more physical cores the better. So this really depends on how heavy the video and photo editing you do are.
I would recommend the Intel build. Have you thought about a hard drive, do you know what operating system you are going to be putting on it? Do you already have a case and a power supply? I would recommend a modular power supply. When you look at cases make sure that the video card that you want can fit inside the case. Going back to the hard drive, I think that a Western Digital Caviar Blue 320 gigabyte is a good selection.
The 955BE is a good little CPU and you can overclock it to get more out of it (not so much with the i3 2100). The main reason to go with the Intel build though is that you can upgrade to a better CPU, like the 2600K, latter on. Your upgrade path is somewhat more limited on the AMD build since none of their current CPUs come close to the 2600k and their new CPUs will need AM3+ boards which aren't out yet.