XP Security?

I just got sick of the problems with 7 and vista on my office machines, so I am switching back to my old XP computers. Old enough to still just have service pack 1 installed. Any suggestions as to concerns about security? Microsoft is making it difficult to get help on this. Any advice as to which free security software to install? Thanks in advance.

What's wrong with 7?

Up date xp to service pack 3 and get Microsoft security essentials free anti virus, its not the best but free and easy.

Thanks SD...I finally figured that out today. To show you how old we are talking about...it took over 700meg updates and downloads and took most of the day. Now, on to the next one!