My current computer is currently five years old. Obsolete by most standards. Since I don't plan to upgrade within three years of purchase, I'm sure whatever model I get will be obsolete soon enough. But you're right, six months is a long time and I definitely won't be putting it together until...
1) What will you be doing with this PC? Gaming? Photoshop? Web browsing? etc
Programming, algorithm testing, software testing, web browsing. Nothing to do with gaming. So any hardware that only makes sense for gaming, please rule it out for me.
2) What's your budget? Are tax and shipping...