1.)The easiest way is to pull out that stick of RAM and check out the sticker on it that says what it is. Since we’re dealing with DDR, the slowest you might be able to find is PC1600, that runs at 200MHz DDR. That’s the equivalent of PC100 SDR SDRAM, and you’ll be fine getting PC2100 DDR.
2.)ECC is an error correction ability of some RAM sticks. This only works if the motherboard supports it and is turned on. For servers where stability is of upmost importance, this is basically a must, but for the home user, it’s just something that can slow down a system that should be stable enough for most uses. You’re not going to be able to make use out of ECC, so don’t pay for something you really won’t/can’t use.
3.)I have no clue as to who makes the Performance brand or what, but I avoid stuff I’m not sure who makes it. I’d go with the Kingston as it does work. However, I would suggest buying something faster than what you currently have instead of limiting yourself to PC2100. For the future’s sake, I’d get no less than PC3200 (400MHz). You probably won’t make good use of the top speed now, but you’ll be in a better position in the future and not be having to buy new RAM to deal with a bottleneck.
With the nForce 2, the dual-channel feature doesn’t really increase performance all that much, but if you later decide to jump to an Intel platform, you’d see a major difference. Still, I’d buy a couple sticks of PC3200, in a 256MB size.
Kingston ValueRAM is fine if you’re not a tweaker, but if you’d like to start playing around, your luck might run out, but it’s still good stuff and some people have had good results when they tweak their ValueRAM.
Other brands that would work well: Crucial, Samsung, Corsair.
