DDR PC3200 & PC2100

My computer at home currently has DDR PC3200 Memory in it, 1 gig worth (2x512mb). I recently obtained 2x512 DDR PC2100 memory sticks. My computer at home is not quite as fast as I'd like it to be to play a game that I like. My question is, is it going to make an increase in speed if I add the PC2100 sticks to my PC? Or will it just slow it down because the computer can only work as fast as the slowest memory it has?

It will slow down RAM access because, as you accurately put, the computer will only talk as fast as the slowest memory module on the RAM bus.

You might be able to manually adjust the clock of the bus and basically OC those 2100s, but you'd invite problems doing so.

On the other hand, your computer might run a little better with twice the memory... hard to say which way it would go.

Thats where I'm left at, I guess I just need to try it and see. Is there anything out there that will test memory speed of a computer? Maybe I can get a for sure answer out of something like that, and I'd be sure to post it for just some bitter knowledge.

Depending on which games you play, which OS you have, and how many background processes you have, it would likely benefit you more to add the extra 2 512MB sticks to increase to 2GB of RAM. If you're on Vista or Windows 7, its a no brainer, use all your RAM. If you're playing older games on a tweaked XP that's not hogging much RAM, you might not want to add the memory. But chances are, if you're noticing slower performance when gaming, you're probably not playing older games could use the extra memory.

The only game I play is World of Warcraft (I know I'm a nerd), I use XP Home, and I havent installed anything on the computer except wow and mcaffee. But I'm wondering if RAM isnt my main problem. I have a NVidia GE Force 4000 series graphics card that might have a bit to do with my slowness, what do you think?

Well first of all mcafee is garbage, I would not run 3200 and 2100 together you would be better off if it was 2700. The graphics card you should be able to run wow on low settings with very little lag.