Something about memory.

[halfdone]

I have a 1 stick of 3200 512mb. Now I also have 3 sticks of 2700 that equals to 512mb. I have all of them inside my computer for 1 gig but I heard that the lower speed memory would be used rather than the faster one. So would my computer perform better with only the 3200 512mb or would it perform better with all of them used. So my question is rather speed vs size.

[squeaky]

Leave them all in. Capacity is more important than speed, since the difference in RAM speed isn't very noticeable, and RAM is made for capacity. Unless you're a ferocious benchmarker, it's better to have a gig of pc2700 opposed to 1/2 gig of pc3200

[Erik]

Memory speed isn't very important but CPU speed is, and the two ARE connected.

The speed your CPU runs at is equal to the FSB (=memory) speed multiplied by some number (the "multiplier").
Make sure you increase the multiplier when you decrease the FSB.
Both settings can be viewed via the BIOS but I've heared not all motherboards allow you to change them both.

Did you even reduce the FSB when you added the pc2700 sticks?
Good quality memory can often run at much higher speeds than indicated.
I wouldn't be surprised if your pc2700 (=166Mhz DDR) runs fine at 200Mhz DDR (the same as pc3200).

[squeaky]

It won't clock down your CPU's FSB, the ration will just change from 1:1 to ~5:4

Depending on the RAM, most value level RAM doesn't overclock very well, so don't count on getting it back up to 1:1