Weird and suspisious processes makes system not working!

[Score1000]

since 10 days ago all of the clients on my network became unreasonably ill! they work very slowly even with a Pentiun full 2.4 and 512 MB of RAM! the software Devs sould work with VS .NET so it kills them to complile a project.
to see what's happening when I go to task manager I see lots of processes with weird name like Amoumain.exe or soundman.exe, defwatch.exe ...(all .exe) are running on the PC even when no application is runnung, but the question mark is there when the CPU and Memory usage is normal! I installed McAfee and Norton with the latest updates but did not found any kind of viruses ot worms. the latest windows patch is also installed, what can I do to make the PCs working for my networ users???????
it is going to be a nightmare to me as a poor Sys Admin, please help.

 

[carrr]

amoumain.exe is for a wheel mouse.
defwatch.exe is Norton.
soundman.exe is Avance SOund Effects Manager.

All legit files. Have you run SpyBot or SpywareBlaster?
You can also, one by one, end tasks that are running and check for increased performance after ending each one.