Desktop resolution

[Bucky Ball]

*-display:1 UNCLAIMED
description: Display controller
product: Advanced Micro Devices [AMD] nee ATI
vendor: Hynix Semiconductor (Hyundai Electronics)
physical id: 0.1
bus info: pci@0000:01:00.1
version: 00
width: 64 bits
clock: 33MHz
capabilities: pm pciexpress bus_master cap_list
configuration: latency=0
resources: memory:f5010000-f501ffff

There is no driver installed for the display controller. The Radeon 1800 does seem to have an appropriate driver installed, though.

[Yellow Pasque]

ATI should be using fglrx and Catalyst Control Centre (control resolution from there) but not sure if that is the case with older cards (although should be).

No. fglrx/Catalyst is not usable/applicable here.

There is no driver installed for the display controller

From what I've seen, it's normal for lshw to report 'Unclaimed' on the secondary controller.

Try playing with xfconf:

xfconf-query -c displays -l
xfconf-query -c displays -p /Default/DVI-0/Resolution