In fact Ubuntu 10.04 or any other Linux based systems are not so vulnerable to viruses and worms because most of these malicious programs were developed for windows platform with .exe executables so they are harmless for ubuntu 10.04.One more fact is that,Ubuntu(or any GNU-Linux OS) security policy and strategy is very secure as compare to other operating system like windows and mac.So If you want to install antivirus software for scanning other media or other drives then Avast Antivirus is a good choice.
Avast antivirus has many edition like FREE,PRO and others but FREE edition is sufficient for common Internet users.

How to Install Avast Antivirus software on Ubuntu 10.04

1. Download avast(FREE Version) from its official website(click below on the download link and then a window will appear-save the .deb file on your computer).
Download Avast for Ubuntu

2. Go to download(or other location where you have just downloaded the avast debian package );Then Open avast4workstation_1.3.0-2_i386.deb with Gdebi package Installer and then click on install Package.

3. Wait until the installation is complete(it will take less than a minute).

4. Now to use avast you will need a valid License Key(Click below and register,they will send you a valid license key by e-mail within 24 hours).
Click here to obtain free license key from avast

5. After getting the key, Go to Applications->Accessories->avast! Antivirus and enter the license key.

6. That’s All…Avast is installed successfully on your ubuntu 10.04.