Hi,
First up, do you plan on doing any gaming? If so, don't get the X1600, its really not very good at all. If you are going to be gaming, what kind of games are you planning to play?
About the CPU, if you are doing gaming then get an Athlon 64, or for dual core, get an X2 3800+. Or if you're not gaming then the 930 is fine, mobo is fine, your memory should not be a problem.
You will need a new power supply, I recommend not to use generic, i hate those dodgy things. You will want around 420-500W, consider looking at the Antec SmartPower range. I always recommend Enermax Noistakers for their excellent quality, stability and they are very quiet, not to mention quite inexpensive (I have one myself). With a Noistaker 485W, you will be good with a bit of headroom for any future upgrades or whatnot.
What sort of case do you have currently? Is it old or new? The problem with your case is that northwoods didn't generate as much heat as some of the modern CPUs such as the pentium d's. so they didn't always design cases that have very high airflows, with an intake fan on the front and another 80mm or 120mm on the back. if its not a recent enough case it could well be worth ditching for the sake of low temperatures.
If you do plan on a new case, it's up to your tastes and budget. A lot of people make really cheap weak plasticy thin steel cases, and i wouldn't trust some of them with my new rigs. But I will say that CoolerMaster do make really good featureful, nice looking quality cases for incredibly low prices.