I haven't looked at the link given...

But for the PCs running Windows on my network (not many to be honest) I use:

AVG free virus scanner on each PC;

Zone Alarm Pro on each computer (As the Pro version has better support for networks) for the firewalls - I can't afford a hardware firewall as of yet, but I may dig out an old un-used PC and install Linux on it and use it as the firewall for the network.

Search and destroy for the spy-ware;

And thats about it... Maybe not the best security but almost all free.
For good free security (well as good as Windoze can be, lol) you could just use the Free AVG and Free Zone Alarm.

These are my recommendations anyway.

If you don't mind paying money, I would go for BlackIce for firewall (and/or a Linux hardware firewall).

I wouldnt recommend using the software on that link. Some of it is known spyware.

As MetalHead said already you should have a good virus scanner...AVG is one of the best free ones...a good firewall....the free ZoneAlarm is okay for normal use..but if you have 25$ get the Pro version...or a hardware firewall which is better than a software firewall. But for the spyware removed I recommend AdAware..because Spybot S&D finds anything that seems wrong...even if it should be there it still tells you that it shouldnt. So you remove it and it screws you over. AdAware references to a libray of spyware and gets more updates.

I haven't actually come accross that using Search and Destroy...

I have used AdAware aswel, but after installing and removing some spy ware (nothing Windows related) I went to shut down the computer at night, and it just restarted, lol. It would not shut down - So I put it down to AdAware as I have heard a lot of stories about AdAware and Windows XP.

Mind you, I was doing some other crazy stuff that day on the computer too, I was hacking at the boot menus, login menues, etc. So that may of been the reason. I prefered AdAware too...

I may install it again, see if I have any problems with it this time.