For virus scanning I'd recommend AVG(Still free).
http://free.grisoft.com/doc/1/lng/us/tpl/v5
p.s. Don't use Norton AV it's a resource hog.
You also might try this site:
http://www.tweakguides.com/
It has tons XP/3D optimizations. (I'd recommend reading and following the XP Guide, but also look at the next site for a bit more.
and finally(most useful to to you)
http://mywebpages.comcast.net/SupportCD/OptimizeXP.html
Check out step 8. This will help you and your brother both.
Also, on a 1Mbit conection you max should only be either 125/128 Kbyte depending on how the 1 Mbit speed was qouted.
The number one thing I'd reccomend if get cable modem
I love 5Mbit downloads most sites don't even keep up.
Breaking Stuff=Fun!,Bug Testing<>Fun!, Bug Testing=Breaking Stuff, so...
Bug Testing=Fun! Hmmmm....
DOES NOT COMPUTE! SYSTEM MALFUNTION!