Simple RAM question

[towhatben]

I currently have 1 x 1 GB of Kingston DDR2 533MHz/PC2-4200 Non-ECC CL4 1.8V Unbuffered Dimm 240 pin Ram.

I'm looking at buying some more. My options are as follows:
1) Buy another stick of the same for £15

2) Buy a Corsair 2GB Kit (2x1GB) DDR2 675MHz/PC2-5400 XMS2 Memory Non-ECC Unbuffered CL4(4-4-4-12) for £30

3) Buy 2 more of the kingston sticks so run 3 x 1GB.

Which of these options is best for the price? I.E would spending £15 more for the faster corsair give an increase in performance equivalent to spending twice the amount?

Thanks

 

[Tmagic650]

Does your motherboard support Dual-Channel memory? If you have 3 memory sockets, it won't support dual channel so go with the 3 Kingston 533's

 

[towhatben]

Apparently it does support dual channel. I have 4 slots, 2 x2 apparently.

Is going for 3 sticks in that case a no no?
Cheers for the help

 

[Tmagic650]

If it is indeed a dual channel motherboard going with the 2GB Corsair "matched pair" would give you better performance overall

 

[towhatben]

Excellent, cheers mate