Here's my 2 cents advice:
CPU: i7-950 looks a little bit overkill to me. From the recent benchmarks I've read the i5 series perform in the same realm as the i7. A recent "Recommended-buy" CPU from Tomshardware suggest the i5-750 or 760. If you overclock an i5 you can even get more performance than the Intel i7 extreme edition. An i5-760 costs 100$ less than the i7-950. With the money saved, you can invest on a more powerful graphic solution or SSD storage, it will have a more significant impact on performance. I suggest you read this recent "best CPU for the money" article from Tomshardware:
http://www.tomshardware.com/reviews/best-gaming-cpu-core-i5-760-core-i7-970,2698-6.html
Motherboard: I agree with you, Asus is not what it used to be. I've heard a lot of good things about Gigabyte. So my next board is probably going to be a Gigabyte. One thing to note, depending on the CPU you choose it might affect your motherboard model, i5 and i7-800 series use socket 1156 and i7-900 series use socket 1366.
PSU: 480W should be enough to run your CPU and GPU. However, as someone else pointed out PSU tend to fatigue over time and be less effective, so it might not be 480W anymore. Not to mention higher chances of failure. If you have extra money you could invest in a bigger PSU, something like 600W or more. It might be useful in the future if you plan to upgrade your GPU or other parts, then you won't have to worry about power. However, if you're on a tight budget you could keep your current PSU and take the risk. But even though your current Enermax is reliable, you never know, *** happens.
RAM: 4 GB should be enough for most applications and games today, but RAM being very cheap, don't be afraid to go for 6 or 8 GB. One advice too, don't go for super fancy tech NASA-like type of RAM. You won't see much of a performance difference compared with cheap value memory. Same thing with speed, don't need to go over 2000 Mhz, your CPU and FSB can't feed it anyway. The sweet spot seems to be with 1333 and 1600Mhz kits right now, but even so, I don't think you would see much of a difference compared with a 1066Mhz kit. And same thing applies with dual-channel and triple-channel technologies too, you're going to see a 5% performance increase at best. So the thing to remember with RAM is: go cheap and keep it simple! You can see for yourself in the following article:
http://www.tomshardware.com/reviews/core-i7-870-1156,2482-9.html
And by the way, why would you want 24 GB of RAM in your system? Unless you run a very particular application that requests this amount of RAM like for high-end rendering and video editing... but seriously 99% of the people don't need so much RAM. And when comes the day you will need 24 GB to run standard applications and games, you will probably need to replace your whole system anyway. For instance, I have 8 GB in my current rig and I never use more than 3, even when I'm gaming or I have many windows opened.
GPU: You should measure the length of your card to make sure it's gonna fit in your case, you'll see, new video cards are quite big. And like I suggested earlier, if you save money on the CPU and RAM, don't be afraid to invest that money in a bigger card if you plan on gaming. For instance, you'll get a significant performance increase if you go from a Radeon 5770 to a 5830 or 5850. I just got myself a new EVGA GTX-460 1 GB and I bought it because I have a mid-tower case and some other cards wouldn't fit in my case. I'm pretty happy with my 460 so far, it's small, cool, silent and fast. A very good bang for the bucks and currently a recommended buy on Tomshardware.
Hope this helps you!