I just got my trifire setup with 5870s, and the problem I am having is that for my Win7 games partition, I installed the 10.1 drivers and then Crysis and Warhead, (nothing else yet) Ran it at 2560*1600 with 8xAA and maxed every setting. Both games I'm getting around 2-5fps under win7. Under winXP, I'm using the same drivers, and getting 30-40+FPS with the EXACT same settings (very playable).
The Win7 parition is on a hdd all by itself it's a Seagate Barracuda 7200.10 250GB drive.
The winXp partition is on a 500GB hdd with 3 paritions on it (one with XP 64, one with Vista64, and one with backup stuff. it's a WD Caviar blue 500GB hard drive
I'm running an ASUS M3A78-T deluxe with 8GB ram, PII965 @ 3.4,
Can win7 really be that big of a difference, or could it be that big of a difference reading from the hard drives??
When you say you maxed all settings, do you max the settings when running them under Windows 7 too, or set them to be equal to Windows XP, meaning running DX9 instead of DX10 and .. is it High setting, instead of Very High?