Computer Running Slow

Hi,
I have a IBM600 Thinkpad that my husband bought for me last year. These are the properties:
Microsoft Internet Explorer Version: 6.0.2800.1106
Cipher Strength: 128
Update Verion: SP1;Q823353
Network ID/Computer Name: IBM600
General Properties: Microsoft Windows 2000
Version 5.00.2195, Service Pack 4

I've had my computer looked at by the GeekSquad to get new updates loaded. I have a D-Link wireless modem connected to my computer. I have Charter Security Suite added for a firewall because my service is through Charter Cable for Hi-Speed internet, I also have Yahoo Anti-Spy and Spybot added. My virus scan is run every 2 days, I run the spy ware at least every 2-3 days and I delete the history, cookies and the temporary internet files. For some reason, my computer tends to run slow even after I do all of that. I tried everything I can think of besides buying a new software package. What could be the problem or what am I doing wrong? Do I need to add a new program or software?

 

Please follow these instructions to tweak your system for performance. If after completing these steps, you are still not satisfied, you may want to consider a hardware upgrade (RAM and CPU prioritized) or following the instructions in the overclocking guide