Install LAMP and mysql in ubuntu9.04 .! Please help me!

Install LAMP and mysql in ubuntu9.04 .! Please help me! -- Linux general technology-Linux technology and application information. For details, refer to the following section. Root @ automatical-desktop :~ # Sudo apt-get install mysql-server
Reading the package list... complete
Analyzing the dependency tree of the software package
Reading status information... complete
The following additional software packages will be installed:
Libhtml-template-perl mysql-server-5.0.
Recommended software packages:
Libipc-sharedcache-perl tinyca mailx
The following [new] software packages will be installed:
Libhtml-template-perl mysql-server mysql-server-5.0
A total of 0 software packages have been upgraded, 3 new software packages have been installed, 0 software packages have to be uninstalled, and 17 software have not been upgraded.
Download the 23.7 KB/MB software package.
After decompression, 79.7 MB of extra space is consumed.
Do you want to continue? [Y/n] y
Get: 1 http://mirror.lupaworld.com jaunty/main libhtml-template-perl 2.9-1 [65.8kB]
Get: 2 http://mirror.lupaworld.com jaunty-updates/main mysql-server 5.1.30really5.0.75-0ubuntu10. 2 [57.2kB]
Download 123kB, time consumed 0 s (138kB/s)
Configuring the software package...
(Reading the database... the system currently has a total of 202741 files and directories installed .)
Extracting the mysql-server-5.0 (from.../mysql-server-5.0_5.1.30really5.0.75-0ubuntu10.2_i386.deb )...
Aborting downgrade from (at least) 5.1 to 5.0.
Dpkg: handle/var/cache/apt/archives/mysql-server-5.0_5.1.30really5.0.75-0ubuntu10.2_i386.deb (-- unpack) error:
The sub-process pre-installation script returns Error 1
The software package libhtml-template-perl was deselected.
Extracting libhtml-template-perl (from.../libhtml-template-perl_2.9-1_all.deb )...
Select the unselected mysql-server software package.
Extracting mysql-server (from.../mysql-server_5.1.30really5.0.75-0ubuntu10.2_all.deb )...
* Stopping MySQL database server mysqld [OK]
Processing the trigger for man-db...
An error occurred during processing:
/Var/cache/apt/archives/mysql-server-5.0_5.1.30really5.0.75-0ubuntu10.2_i386.deb
E: Sub-process/usr/bin/dpkg returned an error code (1)
Root @ automatical-desktop :~ # Sudo apt-get install mysql-server
Reading the package list... complete
Analyzing the dependency tree of the software package
Reading status information... complete
The following additional software packages will be installed:
Mysql-server-5.0
Recommended software packages:
Tinyca mailx
The following [new] software packages will be installed:
Mysql-server mysql-server-5.0
A total of 0 software packages have been upgraded, 2 new software packages have been installed, 0 software packages have to be uninstalled, and 17 software have not been upgraded.
You need to download the 0B/23.6 MB software package.
After decompression, 79.5 MB of extra space is consumed.
Do you want to continue? [Y/n] y
Configuring the software package...
(Reading the database... the system currently has a total of 202749 files and directories installed .)
Extracting the mysql-server-5.0 (from.../mysql-server-5.0_5.1.30really5.0.75-0ubuntu10.2_i386.deb )...
Aborting downgrade from (at least) 5.1 to 5.0.
Dpkg: handle/var/cache/apt/archives/mysql-server-5.0_5.1.30really5.0.75-0ubuntu10.2_i386.deb (-- unpack) error:
The sub-process pre-installation script returns Error 1
Select the unselected mysql-server software package.
Extracting mysql-server (from.../mysql-server_5.1.30really5.0.75-0ubuntu10.2_all.deb )...
* Stopping MySQL database server mysqld [OK]
An error occurred during processing:
/Var/cache/apt/archives/mysql-server-5.0_5.1.30really5.0.75-0ubuntu10.2_i386.deb
E: Sub-process/usr/bin/dpkg returned an error code (1)
Root @ automatical-desktop :~ # Cd/var/cache/apt/archives
Root @ automatical-desktop:/var/cache/apt/archives # ls
Libhtml-template-perl_2.9-1_all.deb
Lock
Mysql-server-5.0_5.1.30really5.0.75-0ubuntu10.2_i386.deb
Mysql-server_5.1.30really5.0.75-0ubuntu10.2_all.deb


I have previously installed mysql 5.1 separately and later installed the LAMP service. MYSQL 5.0 is used in LAMP. Therefore, MYSQL 5.1 is deleted and downloaded. As a result, version 5.0 cannot be installed.
I don't know why. Please be aware of this. Thank you!