Installed XP 32-bit. Good news.

With BIOS 1.1 all values read 10 and 20 instead of 18 and 22.

Performance with the WinRAR bench went up to a bit under 1800KB/s (no optimizations, RAM at default 800MHz CL5, clean install, no drivers and so on).

So, even though I did not test with Vista without SP1 thoroughly, I did earlier notice that my performance went down for some reason (I got higher 3dmarks etc, with Vista RTM), just didn't figure out what caused it... seems it was SP1 and TLB-fix.

My conclusion is simply that SP1 for Vista enables the TLB-fix via software, so regardless of BIOS-version it is enabled... unless bypassed via software (like AOD, which disables it for first core only, though). I should also test with Vista RTM, but since SP1 is coming, performance eventually goes down.

Hope it is not included with XP SP3. Anyone tried the test versions of SP3 to check this out?