I second what skittle said -- but to be absolutely sure, double check what your mobo can handle. depending on the number of slots and maximum ram size -- it may be better to get one stick 1gb or two more 512mb sticks. My p4 system will run dual channel with 3 sticks (1 gb x 2 512 mb sticks) --- but remember dual channel only gives you a 7-10% increase and may not be worth it
If the new RAM you buy have different timings the the old ones. The BIOS will use the timings of the ones that have the highest timings....If set to AUTO...
If Brand X is 5-5-5-15 and brand Y is 4-4-4-12 the BIOS will set both at 5-5-5-15.
And If you overclock or manually set timings in your BIOS make sure the New sticks will run at that speed and or timing... Plus overclocking 4 stick requires more volts the 2 sticks. Some boards will lower DDR400 to DDR333 with 4 sticks(Some Nforce boards).
Wow, that is some serious info. All of which I did not realize was possible. I mean, "partitioning" RAM for different apps? Cool.
Thanks for all the help.
And as a side note, Tom's Hardware Forums are probably the best ones I have ever posted on. Being a noob and asking for advice, I usually get ridiculed or told to bug off. Which is why I try to steer away from posting on forums. But the forum members here actually are very helpful while also being respectful. So thanks for that as well.