Quick Connundrum (RAM)

I am looking to buy some more RAM - well get some more for my PC.

I am using a Biostar M9 939 motherboard, and it has 4 DDR400 slots for RAM.

I currently have Patriot XBLK (2x 512Mb) - which cost me quite a bit back in the day.

However it looks like I will be needing 2Gb for various things. Now would it be best to get another matched pair of Patriot Sticks (2 x 512Mb) - so I would have 4 x 512 in total.

I run them at stock (using a divider) at 2-2-2-5 1T, will I be able to still run the memory at 1T and what would the performance hit be, between the 2 and 4 sticks with regards to speed (not capacity). Will it still work in Dual ?

Or should I get 2 x 1Gb of Corsair RAM, 2-3-3-6 1T. What would the performance difference be between these at stock, using their rated timings?

Cheers

Ian

I recently bought an extra pair of ram and now I run 4x512mb.

Original pair: Geil Value
Recent pair: Geil PC4000

Initially the ram ran at DDR 333 but a quick change in the bios, the ram is now running at DDR 400.
However, it is running at 2T rather than 1T.

In terms of performance I can't compare with 2 x1gb but some games seem to run slightly smoother (notably Oblivion) although I haven't really had the chance to test out otehr stuff.
3DMark seems to have no change at all, but I've read the scores are synthetic and don't reflect what impact the ram will have. I have read performance difference between 2x1gb Vs 4x512mb is a 3-5% slowdown on 4 x512mb.

If you're after performance I'd suggest 2 x1gb so you can run at 1T but if you just need an extra gig of ram then an extra pair of good ram will be so much easier on your pocket!

Hope it helps, but other users might have other suggestions.