Run all these free Programmes and you'll safe as houses Dan

AVG free is fine for anti Virus infact it's excellent

http://www.grisoft.com/us/us_dwnl_free.php

Ad-aware
http://www.lavasoftusa.com/support/download/

Spybot - Search & Destroy
www.safer-networking.org/index.php?page=download

Both of the above programs scan your computer for spyware and other malicious files that can be picked up online. When they have finished scanning they allow you to choose to remove these files. You should download and install both Ad-aware and Spybot S&D then, before scanning, use the built in 'update' feature in each down keep the definition files up-to-date.

SpywareBlaster
http://www.javacoolsoftware.com/sbdownload.html

Whereas Ad-aware and Spybot search and clean your computer, SpywareBlaster stops the spyware/adware from coming back. Install, update, then enable all protection to keep your computer much safer.

CWShredder
http://www.spywareinfo.com/~merijn/downloads.html

CWShredder scans for specific browser hijackers that are notoriously difficult to get rid of and can be missed by the above programs. A browser hijacker takes over your home page and various search engines and is designed to 'force' you to view certain websites and adverts instead of what you want to see.

Firewall

ZoneAlarm
http://www.zonelabs.com/

There are three versions of ZoneAlarm available. The free version (ZoneAlarm), as well as ZoneAlarm Plus and ZoneAlarm Pro. The free version is perfectly suitable for home use.