Have you made sure all your drivers and patches are up to date ?
A load more RAM certainly wouldn't go a miss. XP runs best with at least 512Mb ;)
Worth try are some other anti spyware/virus apps and some system maintenance.
Most of these steps will work with any Operating System
Here's some simple steps for you to take.
1/ Remove temp files and other rubbish form your system, either with inbuilt Disc Clean up or
CCleaner. (Ccleaner also has a good registry cleaner as well)
(Disc clean up; open my computer > right click your C: drive > properties > Disc clean up button on general tab. Let it run and select everything)
2/ Defrag; open my computer > right click your C: drive > properties > Tools tab > Defragament now button.
3/ Error checking; open my computer > right click your C: drive > properties > Tools tab > Top button > check now. Check BOTH boxes, OK the error message and reboot.
4/ Page file; Right click 'my computer' > properties > advanced tab > Performance settings button > advanced tab > Virtual memory (near the bottom). To make things easier for you select System managed size > click set > then OK's all the way out again. (
I suggest 'system managed' as there is no consensus on min and max sizes to set)
5/ To make sure everything is running fine also run both anti virus and anti spyware apps (make sure that they are updated first ;)) (
AVG is good and free AV)
(A couple of good removal tools are
Spybot and
Adaware)
Spybot has a good feature called Immunize which stops a whole bunch of malware installing itself in the first place.
ALso an on line virus and spyware scanner is
Trend Housecall