A lot of viruses, worms and spy-ware keep infesting my computer. the reason (i think) is that my neighbours kids keep downloading and running software from the net. is there any way to automate this and avoid the chore of manual scans?

You should let us know what security software is installed on your pc: firewall, antivirus software, antispyware. Antivirus software and antispyware usually have "schedulers" and you can set them to perform automatic scans. It is also very important to keep your Windows updated.

the setup i have on my system is:
firewall: none
a/v: avast
a/s: spy-bot s&d

how do i automate the task of running these tasks automatically.. as well as windows updates?

To automate a task go to:
Start > All Programs > Accessories > System Tools > Scheduled Tasks
And from there you can schedule Windows to run any program at any given time if you are having trouble remembering to do it yourself.

You can also turn on automatic updates for Windows if you have turned them off:
Right click My Computer > Properties > Automatic Updates tab > check the Automatic box > Apply

Another way is to tell the parents to get their own PC.