Protecting my old [second] pc - wireless networked - with Norton

Dear Community,

 

I have a good 5 year old pc running Windows XP with a fully paid up version of Norton Antivirus 2009.

 

This is wireless networked to an older 9 year old pc running Windows 98 SE using a very old Norton AntiVirus Version 4.0 requiring a manual Live Update etc.

 

My questions are:

 

(a) - is the old pc adequately protected? [ I suspect not - but I may bin it eventually - and don't want to spend too much]

(b) - can a security compromise on the old pc harm the newer pc (which is well protected with Norton 2009) as they are networked

(c) - if I want to upgrade the security on the old pc what is the cheapest way of doing this? I don't pay anything for the old pc as Norton 4.0 was before the days of paid subscriptions.

(d) - Norton 4.0 only has  74212 virus definitions [last update 11-OCT-08]. is this the full quota of virus definitions available? or just a selection i.e., just current virus definitions ONLY for the viruses that existed in the days of Norton 4.