I've just installed linux on my main desktop for the first time ever (I've been running ubuntu on my laptop for a while). My desktop has a Radeon X1900XTX and Im confused about which drivers to use. I notice from the Ubuntu repositories there are the following:

Xorg-driver-fglrx (AMDs propriety driver) (I have these installed at the moment)
Xorg-driver-fglrx-envy (I guess this is also AMDs propriety driver whats the difference between this one and the other?)

So it appears theres six apparently very different packages other than the fglrx package which others support my X1900 and which would be the best to use? Basically I'd like it to work the way XP does it extend my desktop to the other screen and be able to use hardware acceleration on both.

The problem is that the dual screeen works correctly at the login screen but then goes to clone mode after i've logged in how does that work? from what I've noticed the login screen seems to use a different config to the main desktop as my laptop has the login screen running at 1280x800 and once logged in the resolution is 1680x1050 which is native res for the screen. Why don't they both read from the same hymm sheet so to speak. See this is why I'm confused as I don't fully understand whats going off. Also why the hell did ubuntu change the display-config-gtk for that new one in 8.04 its rubbish and doesn't do anything remotely useful