What ram set up is best?

2x2 (If running a 64-bit OS)

2x1 is simply the cheapest at this time. Also the best if running a 32-bit OS.

Well money and OS is no problem,i'm just wondering if the extra GB are going to reguire more voltage and wattage,and if they're going to get in the way of an overclocked PC,other than that it really is no big deal as far as the money goes.

With the current CPU architectures and caches, RAM configuration does not matter. I believe Toms did an article about this.
http://www.tomshardware.com/2007/10/17/parallel_process...

If you get a 64-bit OS, then go for 2x2GB, or even just one stick of 2GB if you can't afford two. The performance increase is negligible.

The voltage doesn't change between configurations.
The 1T timing of the memory will be 2T if running 4 sticks.
Overclocking results are better with 2 sticks.
There will be a slight increase in Wattage due to additional sticks.

Ok so of course that means that 2x2 = better than 4x1!

So the question becomes 4x2 vs 2x2.

Voltage remains the same,slight increase of wattage,more ram but not better OC,as far as the first case goes,right?

Whats 1T/2T?And can you plz be more specific when you say 2 sticks are best?

2T is the command rate.
Less sticks better overclock.
Good brands: Corsair, Patriot, OCZ and Crucial.
DDR2-800 the most popular DDR2 memory.
If you have a 32-bit system, stick with 2x1. A 32 bit system will not recognize more than ~3.5 GB.
If you have a 64-bit system, then 2x2 or 4x2 is okay.