how to format disks to re-install ubuntu

[okkie]

my system is sick after gutsy install. gutsy cannot handle my ati radeon 9250 card.i want to re-install feisty which doesn't have the problem.at this point computer cannot read 7.04 installation disk.i put all info needed to disk.now need to wipe both harddisks to start new installation.
what must i do please ?

[Manchunian]

Can you explain how your disk is currently partitioned? Is Ubuntu the only thing on your computer, or is it a dual boot? If so, what is the other operating system? Windows? Suse? Bsd?
But, okkie, it seems to me that you're throwing the baby out with the bathwater. What mesures have you done to solve your problem? It's always tempting to re-install when things go wrong, but this should be a last resort. How about you tell us how you went about updating from Feisty to Gusty? Did you do a system upgrade via apt get? If so, it's normal that you have problems with your graphics card: you need to re-install it.

[devils casper]

my system is sick after gutsy install. gutsy cannot handle my ati radeon 9250 card.

What have you tried to install ATI driver?

i want to re-install feisty which doesn't have the problem.at this point computer cannot read 7.04 installation disk.

How did you burn 7.04 .iso image? Have tried same CD on other machine?

i put all info needed to disk.now need to wipe both harddisks to start new installation.
what must i do please ?

If you want to go for fresh install then boot up from any Ubuntu CD and open GParted Partition Manager. Its in Menu. Delete all Partitions and start installation.