I've just downloaded and installed XAMPP on Ubuntu 10.4.
The only problem I had was that Apache was already installed but I stopped it loading :
"update-rc.d -f apache2 remove"
When I started "http://localhost" the first time I got the default page from "/var"
but F5 (reload) cleared that and I got the XAMPP start page OK.
All OK except for 'phpmyadmin' I get "Existing configuration file (./config.inc.php) is not readable. "
After looking at forum I thought that this was a permissions problems although I had changed owner.
I set it to be universally accessible :
"-rw-rw-rw- 1 iain iain 1352 2010-10-13 17:41 config.inc.php"
but still get the error message.
(I'm logging in as 'lampp' as suggested)