im just thinking about what is faster dual channel 4gb 2 -2 gb vs two dual channel 4 x 1gb???
can i install single channel memory or triple channel on dual channel 4 dimm slots???
There is no difference in performance, you are using two channels either way.
The 2 x 2gb is prefereble, for two reasons:
1) It preserves your option to upgrade to 8gb without waste.
2) It is easier to overclock with two sticks vs. 4.
re: second question; yes you can.
Ram is not single/dual/triple channel. It is sold in single/dual/triple kits to insure that all the sticks in your pc are the same characteristics.
That is a good thing since some motherboards can be very sensitive to mismatched ram.