Can I keep using Ubuntu 9.04 if it's outdated?
I tried to upgrade (9.04 to 9.10 of course)... 'Fetching the upgrade failed. There may be a network problem.'
Any suggestions or ways to work around this problem?
Ubuntu 9.10 is beyond EOL (End of Life). You might be able to upgrade if you specify the old mirror, but, realistically you are almost certainly better off installing Lubuntu 11.10.
For an older mirror, see Can I keep using Ubuntu 9.04 if it's outdated?
In the absence of a CD drive , can you boot a flash drive ? If so, you can make a bootable flash drive with Unetbootin .
bodhi.zazen was right on it with the lubuntu. Don't forget that there are tons of other alternative distros to consider when dealing with an older computer. When I'm trying to make better use of old hardware, the first disro I usually try is simply Debian. I'll trial some different interfaces like lxde, xfce, fluxbox, and the like until I find one that works well with my machine's resources.