Need advice on adding more memory to my system.

I am in the market for some more memory, but I have so many options that I do not know what to do.

Here is my system:
P4c 2.8
Abit IC7-G
2x512 Corsair PC3500PT set at 400mhz and 2-3-3-6
BFGtech 6800 Ultra OC
WD1800JB
Antec True480

I WANT an additional 2x512Mb of ram but I don't know that memory would be best to get right now since the stuff I have is discontinued.

I am looking at TwinXPC3200C2PT right now, but I am worried I will not be able to keep my 2-3-3-6 settings. I will get these IF I can keep my latency settings.

Basically what I really want is to have 4x512 set at 400Mhz and AT LEAST set 2-3-3-6. I will get 4 new sticks of memory if I have to aswell.

What is my best option?

One mans throw-away is another mans god-box. Help friends in need, I always do!!
Then again, having extra parts are great for making dedicated servers for LAN parties!!!!

I do all sorts of things INCLUDING heavy duty video encoding.

One mans throw-away is another mans god-box. Help friends in need, I always do!!
Then again, having extra parts are great for making dedicated servers for LAN parties!!!!