I not sure what you mean by (1 G of ram)
are you sure its not 128,256,or 512


but it sound like you have tons of software running in the background and are you using limewire free or pro its a big difference

I would start by start/run/type msconfig/startup tab/disable all/apply/ok/restart/ defrag your hardrive/IE/tools/Internet options/advanced/restore defaults......

thats a good start

then do a full scan at www.pcpitstop.com or something

This is just one approach..............good luck