Dell workstation performing slowly

I have a Dell Inspiron 410 P-III 700mhz 256meg PC 100 RAM on Win 98 SE running very slowly. We just re-installed the OS, new drivers and apps without any problems. The computer’s performance has not improved. The machine usually runs Outlook 97, and Winamp with Mcafee in the background constantly. When an application is opened, the mouse pointer skips or stops moving and winamp will skip or lock-up. A slower Athalon with less ram performs better. With nothing running system resources Sit atabout 80%. What can I do to make this thing perform better?