It's not practical to have two parallel discussions. Too confusing. So anybody interested please go to http://forums.cnet.com/5208-6035-0.html?messageID=2574168
Here's an odd problem.
My computer had 512mb of RAM (2x256mb Corsair TWINX-3200C2 DDR) DIMMs. Today I bought two 1gb sticks (Corsair Value Select 3200C2 DDR) to take my total up to 2.5gb of ram.
When I installed the new ram, XP decided that it would no longer boot. It got up to the "welcome" screen and then went blue-screen on me. I can't tell what it says because it reboots too quickly for me to see.
So, I tried taking out the original RAM and only installing the new stuff in the motherboard's (ASUS A7V880) recommended configuration. Doing this meant the computer would not even get to the boot screen, instead falling over half-way through boot (as seen in safe-mode) and restarting.
The interesting thing is that when I use only one of the sticks, XP will start fine. Swap them over to test them both, and XP still works. Add the old ram in with one of the new, and again XP works fine. The problem only occurs when I install both sticks in any configuration.
The motherboard is rated up to 4gb (1gb in each slot) and XP is the same, so I'm at a loss as to what the problem is. The RAM itself is working fine, just not both together.