Free Firewall that is better than Windows own firewall – ZoneAlarm
http://www.zonealarm.com/
Download the free version on this page:
http://www.zonealarm.com/store/make pleased/catalog/harvest/zonealarm_free_firewall_b.jsp

Free anti-spyware – Spybot Search and End
http://www.safer-networking.org/

Install this and it will scan every file (and the Registry) on your computer for spyware and crimeware. This can take over 20 minutes.
If it removes some spyware/crimeware, shut the computer down, restart, and run it again, because some spyware is very excellent at hiding behind other spyware. Keep running it in anticipation of it reports no spyware.

Free anti-virus – AVG Free
http://free.avg.com/

Now install this and let it run just like Spybot was running, over and over in anticipation of it reports no viruses present.

You will have to update Spybot and AVG every day because the virus and crimeware programmers are putting out new stuff every day.

It’s a never-ending battle.

The simplest way to fix it is by Malwarebyte’s Anti-Malware (Download it, update it, do a full scan, and remove everything it finds).

I would also recommend the following programs to make the removal simpler and make sure you don’t get infected again in the prospect:
Avira AntiVir Personal
Spyware Doctor Starter Journal

Some infections my require a professional to remove. For a fantastic free prorgam that possibly able to help your issues are AVG and Malwarebytes and both can be downloaded from here:
http://www.nicklockard.com/Downloads.html

Virus and spyware infections are the number one cause of Identity Theft and Fraud you can learn more here about them:
http://www.nicklockard.com/Wiki%20XP%20&%20Vista%20Software%20Infections.html

for free advice follow this link