Ubuntu 13.04 with old (radeon HD 4850) graphic card

Ubuntu 13.04 with old (radeon HD 4850) graphic card

I've just installed Ubuntu 13.04 and I think I may have issues with the graphic card.
Its fan is just running very fast (and noisy).
I tried to check the temperature using sensors and got the following:
coretemp-isa-0000
Adapter: ISA adapter
Core 0:       +48.0°C  (high = +84.0°C, crit = +100.0°C)
Core 1:       +47.0°C  (high = +84.0°C, crit = +100.0°C)
Core 2:       +46.0°C  (high = +84.0°C, crit = +100.0°C)
Core 3:       +47.0°C  (high = +84.0°C, crit = +100.0°C)

it8718-isa-0290
Adapter: ISA adapter
in0:          +1.12 V  (min =  +0.00 V, max =  +4.08 V)
in1:          +1.89 V  (min =  +0.00 V, max =  +4.08 V)
in2:          +3.30 V  (min =  +0.00 V, max =  +4.08 V)
+5V:          +2.99 V  (min =  +0.00 V, max =  +4.08 V)
in4:          +0.45 V  (min =  +0.00 V, max =  +4.08 V)
in5:          +0.11 V  (min =  +0.00 V, max =  +4.08 V)
in6:          +0.10 V  (min =  +0.00 V, max =  +4.08 V)
in7:          +3.20 V  (min =  +0.00 V, max =  +4.08 V)
Vbat:         +3.28 V 
fan1:           0 RPM  (min =    0 RPM)
fan2:           0 RPM  (min =    0 RPM)
fan3:         477 RPM  (min =    0 RPM)
fan4:           0 RPM  (min =    0 RPM)
temp1:        +44.0°C  (low  = +127.0°C, high = +127.0°C)  sensor = thermistor
temp2:        +43.0°C  (low  = +127.0°C, high = +127.0°C)  sensor = thermal diode
temp3:         -2.0°C  (low  = +127.0°C, high = +127.0°C)  sensor = thermistor
intrusion0:  ALARM

radeon-pci-0100
Adapter: PCI adapter
temp1:       +113.0°C
IIUC - the temperature is 113.0C is this a normal temperature? Is this why the fan is running fast? Until yesterday I had Windows 7 on this same machine and I haven't had any problems with the GPU fan.
Might be a drivers issue, I tried to install the driver for AMD/ATI web site and failed (something about required packages missing - checked the logs to see what is missing and found out it is installed).
I'd appreciate any help here.
Thanks,
Itay