Ok so I've finally got round to adding a 2nd monitor to my rig. Running PinguyOS dual mode glory.

Everything is working fine except for Compiz/Desktop effects. The card i have is a ATI Radeon 9550. The main monitor i use is a Samsung Syncmaster T200HD. Compiz has always worked fine at resolution of 1680 x 1050 by itself before adding a 2nd monitor.
After a little searching about i believe that the driver i am using is the default "radeon" driver. And the ATI Catalyst drivers. (have tried anyway). No longer support my card. And it is not possible to use any old drivers on ubuntu 10.04 from previous versions. So I am stuck with the default drivers.
Compiz Also works fine when the desktop is set to duplicate on both screens. But I am "extending" the desktop on to the 2nd monitor as i do not want to duplicate my desktop on 2 screens, and this is where i am having problems.
When I have the screens set to extend, the desktop effects switch off. Now i beleive this is something to do with resolutions being over a certain size i read?. I am not sure if this is true.
I am running my Samsung syncmaster T200HD at 1680 x 1050, and my old CRT at a reslution of 1280 x 1024.
I have tried reducing these resolutions to a very low resolution on both monitors (still set to extend) but trying to enable desktop effects still does not work.
Here is some terminal information below, if it is of any help?.
Thanks.
Running this in the terminal , i got the following.
hwinfo --gfxcard
23: PCI 100.0: 0300 VGA compatible controller (VGA)
[Created at pci.318]
UDI: /org/freedesktop/Hal/devices/pci_1002_4153
Unique ID: VCu0.yvUasOMnfI3
Parent ID: vSkL.ITQqGs0XM26
SysFS ID: /devices/pci0000:00/0000:00:01.0/0000:01:00.0
SysFS BusID: 0000:01:00.0
Hardware Class: graphics card
Model: "ATI RV350 AS"
Vendor: pci 0x1002 "ATI Technologies Inc"
Device: pci 0x4153 "RV350 AS"
SubVendor: pci 0x148c "C.P. Technology Co. Ltd"
SubDevice: pci 0x2087
Driver: "radeon"
Driver Modules: "drm"
Memory Range: 0xf0000000-0xf7ffffff (rw,prefetchable)
I/O Ports: 0xde00-0xdeff (rw)
Memory Range: 0xfe9e0000-0xfe9effff (rw,non-prefetchable)
Memory Range: 0xfea00000-0xfea1ffff (ro,prefetchable,disabled)
IRQ: 16 (197302 events)
I/O Ports: 0x3c0-0x3df (rw)
Module Alias: "pci:v00001002d00004153sv0000148Csd00002087bc03sc00i00"
Driver Info #0:
XFree86 v4 Server Module: radeon
Driver Info #1:
XFree86 v4 Server Module: radeon
3D Support: yes
Extensions: dri
Config Status: cfg=new, avail=yes, need=no, active=unknown
Attached to: #10 (PCI bridge)
24: PCI 100.1: 0380 Display controller
[Created at pci.318]
UDI: /org/freedesktop/Hal/devices/pci_1002_4173
Unique ID: NXNs.xaX+Y0hKOmF
Parent ID: vSkL.ITQqGs0XM26
SysFS ID: /devices/pci0000:00/0000:00:01.0/0000:01:00.1
SysFS BusID: 0000:01:00.1
Hardware Class: graphics card
Model: "ATI RV350 AS [Radeon 9550] (Secondary)"
Vendor: pci 0x1002 "ATI Technologies Inc"
Device: pci 0x4173 "RV350 AS [Radeon 9550] (Secondary)"
SubVendor: pci 0x148c "C.P. Technology Co. Ltd"
SubDevice: pci 0x2086
Memory Range: 0xe8000000-0xefffffff (rw,prefetchable)
Memory Range: 0xfe9f0000-0xfe9fffff (rw,non-prefetchable)
Module Alias: "pci:v00001002d00004173sv0000148Csd00002086bc03sc80i00"
Config Status: cfg=new, avail=yes, need=no, active=unknown
Attached to: #10 (PCI bridge)