*UPDATE*
I got Windows to boot up with both sticks with the timings in BIOS set to "auto". Windows detects 2GB.
I feel pretty stupid actually because originally I was trying to boot Windows up from Hibernation and it was failing. I assumed it was the ram but apparantley something just went wrong with the hibernation. I booted Windows normally and everything works so far.
I haven't tested games or checked if the timings, voltages, etc. are correct. Just wanted to note that my main problem is solved.