|"major pc lag for no reason"|
Obviously there's a reason...you just don't know what it is yet.
to start with, 256MB isn't a lot of RAM for XP. It may not be the cause of the lag, but adding at least another 256MB would definitely increase overall performance.
I don't get the comment about "200mhz front side bus". The P3 933MHz CPU runs at 133MHz FSB although it *may* be referred to as 266MHz FSB. If it's running at 200MHz FSB, it would mean the CPU frequency is set at 100MHz & the CPU would be running at 700MHz instead of 933MHz.
What video card are you running?
"i did some testing and when i close explorer in task manager the lag goes completely away"
Normally if you "end process" explorer.exe in Task Manager, you will lose the desktop icons, start menu, taskbar, etc, & will be forced to reboot (I just tried it to confirm)...if this isn't happening, my guess is you have some sort of infection.