here are the minimum system requirements for WinXP
http://support.microsoft.com/kb/314865
and
http://mywebpages.comcast.net/Suppor...ments.html#Pro
your RAM will be ok to run this.
if you dont have a CD then well there is no option, unless you want to buy one.
Well a firewall is better than nothing and since you have win98 which as i have said it totally unsecure by now you should really get one, especially having a network you should consider getting it. possibly even get xp on it if you are willing to buy it.