install both version of ubuntu 8.04 and 9.10

Ubuntu 9.10 is not supported any more,and I think same thing is with 8.04. Maybe it is better to install 10.4 (also LTS as 8.04) and after that 110.4.I know tis is not direct answer to your question,but maybe it will help.If I misunderstand you,please let me know.

As said zvacet, both are now unsupported. Could you explain why you want to use both versions.

Thanks for your answers I just want to install version 9.10 so that I can get connected to wireless internet in my country i.e. India, as many mobile internet connections do not support version 8.04. If I'm unable to do anything I suppose I have option of going to windows and then installing version 9.10 which is supported by company MTS (www.mtsindia.in) . If you have any other suggestion please let me know. Wire internet is also not available in my area.
   Thanks

1) Make a Ubuntu 9.10 CD, boot on it, select "Try" instead of "Install" and check that WIFI is supported for your hardware. If not, you will not be able to install 9.10. Ubuntu CD will only support English. If you want another language, you'll have to get DVD version, which has foreign languages. I don't if it have also more WIFI chip drivers.
2) 9.10 is an unsupported version (even if it is a good version). If you can, use 10.04.2 instead of 9.10. 10.04.2 is a LTS, which will be supported until 13.04.
3) You didn't explain why you use BOTH version. Using a single version will be easier, as you will avoid Linux multi-boot. And worse, 8.10 use Grub Legacy and 9.10 use Grub2, so you will have to choose between or install boot chain-loading. So if you can, use only a single Ubuntu on computer.
4) If you really need both distro, make a backup of your data. Then boot on Ubuntu CD, choose "Try" instead of "Install", then Administration->System->Gparted partition editor. You will see a swap partition and one or many ext4 partitions. You will need to resize ext4 partition to make place for 9.10 files. If you make a 3 ext4 partition scheme like:
a) "/" for 8.10
b) "/" for 9.10
c) "/home"
You could have conflict between configuration files of software which have not same version on both system. To avoid this, you need to have a home folder in each distro "/" partition, and to make a third partition which holds only data.