I have 4 x 2GB of 800Mhz Patriot RAM. I believe the timing is 5-5-5-12. It's fairly new, only a couple months, but it's already starting to have problems. I think there is at least one bad stick. Although I could just return that one, I would rather return all of them at once than wait and see if another goes bad. My question is, for the replacement RAM, would it be better/faster to have 8GB of RAM (which I know is overkill) or 4GB of the fastest RAM my board can handle? I don't work with huge files or am an extreme gamer, and I can already hear the shouts that 4GB is already way too much (I'm running XP Pro). Theoretically, however, which would you say is faster?

XP Pro 32 bit edition only recognizes 3.3GB of RAM. 1GB RAM vs 3 GB RAM=big difference. PC800 vs PC1333=little performance difference

How do you know you have one stick dead?

With 4xdimms installed you may have to bump voltage a bit to run stable. Try seperate sticks and run Memtest86+ to see if you get some errors.