I have installed on my friend old computer Ubuntu 11.10 but it's slower then Windows XP. Probably because of drivers for graphic card - Radeon 9200. Can I install open source drivers for it?
Open source drivers (the only ones you can use with your card so dont try the fglrx packages) are active by default during install. You dont need to install anything else.
What you need to do is use Ubuntu2D instead of the default Ubuntu3D desktop since this card is way to old to support the 3d acceleration necessary for Ubuntu3D.