I too am trying various two-headed approaches.  The details are well 
discribed in the Xinerama HOWTOs.  It's about a 1-step process, but 
worth it.

I previously had it working (RH 7.1 & W98SE) on my 233 MHz Pentium 
that had two similar ATI brand PCI cards.  When I upgraded to an AMD 
900, the motherboard has an on-board SiS AGP.  M$win works with one 
ATI & the SiS, but Linux will do either one, but not both.  I bought 
a Matrox G450 dual-port card and the problems began.  W98 does not 
like it, and I haven't done the Xinerama config (I'm moving to 
Mandrake 8.1, too).

So check the HOWTOs, but my poor mixed-card experience and the fact 
that Mandrake actually specs Matrox (on the box) for dual-head use 
tend to say you may be disappointed.

Gene

From:           	Mark Anderson <stoneaglewolf@yahoo.com>
Subject:        	Dual monitors question
To:             	plug-discuss@lists.plug.phoenix.az.us
Send reply to:  	plug-discuss@lists.plug.phoenix.az.us
Date sent:      	Sun, 17 Feb 2002 09:30:23 -0800 (PST)

> I have an AMD 1.5ghz with 1.5mb of ram.  I installed a AGP gforce 2 mmx card with a 21" compac 
> monitor.  I am curious if I can install a generic PCI or ISA video card and 15" monitor. Will I be
> able to control the resolutions of each monitor seperately.
> 
> Mark 
> 
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