If you have the itch, it is time to scratch it. Particularly after 4 1/2 years.
There will always be something better on the horizon, and if you wait for the next best thing, you will wait forever.
Today's cpu's are very capable. If you are looking at a $200 cpu like the 2500K, you will still feel good when ivy bridge shows up in April.
A H67/Z68/P67 based motherboard will preserve your option to go to ivy bridge. I bet you won't need to.
As to graphics, it is very competitive now. I expect the 7000 series to launch before kepler Amd wil have little incentive to cut prices if it is clearly superior.
Whatever you buy today you can sell and replace in the next year or two.
I don't see how ram can get much cheaper. Today is a great time to buy ram.
On the hard drives, prices are high, I would push that off for a while. SSD's should be a part of your build, and prices are coming down there. Still, a ssd is probably the best thing you can do today for basic os performance.
Do not be afraid to spend money on parts that you love, or will last for several generations of rebuilds.
Get a case you love. Spend more if you have to. You will see and touch it every day.
Get a great monitor. Same reason.
Spend $100 on a mechanical keyboard.
Get a quality psu of good strength. A 650w psu can handle a GTX580, and likely future graphics cards also.
Seasonic, Antec, XFX, PC P&C, and Corsair are quality brands that should last.
Go to a local store and test out the mice. Get one you love.