If you aren't going to Overclock, I wouldnt worry about 1t or HTT. Let the BIOS autoconfig everything, in most cases it will be pretty close to where you need to be. As you learn more you can wade into that stuff later and start tinkering.
The Dual Cores are well worth it IMO. I am running a Dual Core Opteron equivilant of the X2 4800 and it works just fine with this board. As for if you need it or not, well that only you can answer. I am not a benchmark guy, but I can tell you I noticed a big gain in system responsiveness upgrading to my dual core over a single core A64 Winchester at the same speed. I use my PC for games, DVD shrink, Internet, etc.
As for memory, I am using 2 x 1GB sticks of Patriot, and a Seasonic S12-600W power supply and they work just dandy. You can probibly get away with a smaller, less expesnive power supply depending on what you are running, and there are several different quality brands of memory out now so take your pick.