Next I would take a look at the Task Manager and see what processes are running. You can expand the header to I/O reads and writes. Google the processes with the higher traffic. You are likely to be amazed how much stuff is running.

Virus scanners take the system to its knees. On my 2000+ era P4 (940MHz), I load Defender, let it do its detailed scan, run it for a few days and uninstall it.

I would also make more room on the disk by deleting the entire ..
temp directory and all internet temp files (or let system cleanup do that) to create sufficient space for the swap file. Check the swap file setting (read up on what is recommended, I use something like 5x native memory size).

I assume you have Win-XP which does not support the newest IE. I would use Chrome which tends to load web pages noticeably faster (including LGF).

All said, do not expect to watch movies on this hardware without stuttering.

Al the best!