[gilesgraphics]

Netbooks are never going to win any races by their very design

First thing is RAM Max it (all atom based netbooks can take 2GB)
Then look at the the services which are starting up automatically
A lot of these are probably not needed for what you are doing with a netbook.
Get rid of most of the start up items and unwanted programs found in the task bar.. most of the crap manufacturers put in is just pure bloat.. for example mine HAD a complete media suite .. DVD player etc and burning software.. in a machine with no ROM
If your running live messenger stop it from running at start up and only have it on demand (the option for this is in messenger).
They all seem to have a 60 trial of Office Home.. uninstall it, its updater, registration and upgrader!
McAffee Internet Security seems to pandemic on all the XP netbooks I have seen.. it is resource hungry and I don't rate it.. dump it
AVG free is fine for most things and has a small footprint.
ESET Nod32 is the best AV if you are willing to pay.. security suite is not worth it.. get commodo free firewall instead (just the firewall AV is crap)

Mine now runs just fine and I have even been able to do some light editing of large photos in Photoshop 7!