There are many things you can do:

Prevention is better than Cure!

There many viruses and scams out there, and you'd be forgiven for thinking they are unavoidable, however, there are many ways to prevent attacks. (Below is a brief explanation of some of the ways we can do this, for further information please see relevant sections.)

Anti Virus Software

There are many programs available to protect you from hackers, trojans and viruses. Anti Virus software will help protect you from most of these viruses, but you have to ensure these programs are kept uptodate as there are 1,000s of new viruses available everyday.
If they are not kept uptodate then you are NOT protected against the latest viruses.
Use this program to scan your files, floppy disks and any downloads from the internet for any known viruses.
Once you have viruses on your PC, some are not so easy to remove, as they can reside within the operating system, if you are not an experienced with the operating system files it is best to seek expert advice.

 Filtering Software

These programs give you parental control over the what the child is allowed to do on his/her/your computer. When first installed everything is restricted and can prevent your access too.
You need to set yourself up as an administrator so that you can change the settings to allow yourself access, but not the child.
Refer to the Installation Manual for instructions on setting up.
Never give the child the password, as it won't take them long to work out how to change the settings!!

Popup's

These programs are little "Popup" boxes, with adverts and sometimes pornographic images that appear when you open a website or log onto the internet, you can download a Google Toolbar to prevent most popup's from appearing, or use a popup blocker software, but if you find you are still getting lots of pornographic popup's then there is a good chance your PC may be infected with a virus.

Spyware

These are programs are like a window into your PC, they track your surfing habits and can gather personal information about you.
Use a good Firewall and Spyware Software to protect against attacks.

Firewall's

This is a program is like a gateway to your computer, you can block the entrance to your PC and restrict access. This will stop most hackers using and looking at the files on your PC.

To find out what operating system you have;

From the desktop,
Right Click on MyComputer,
Select Properties.
This should tell you what Operating System you are using.