Yah for sure been threw the computer pains,
but heck thats a pretty old system, you can find something alot newer on craigslist for really cheap.
otherwise their is so many things in XP and windows in general that runs in the background, that works ok with newer computers, but a old processor really gets tied down, with so much junk running in the background.
Most antivirus programs are just resource hogs, and every program or app has krap auto update.....real convenient i know.
But just having windows update on and something like norton running can just kill a older machine. dont forget adobe, or firefox, or itunes or almost every software has auto update...turn all that junk off man. auto updates bunch of stuff always running in the background..kill it
XP made a big deal about being able to have multiple user on a system. if you create a limited account and use that for the internet it solves 90% of all virus problems. and you simply dont need a anti virus or firewall, complete resource hog.
limited accounts are unable to install software, but almost everybody goes on the internet as a administrator. which has full rights so any virus that comes in will install right away. a limited account wont do that, combined with fire fox and the normal windows security, almost nothing comes in.
the best free cleaners/ scanners are
Spybot and
Malwarebytes