Real-time spyware monitor

[BigDaddy]

In a school classroom we have 12 PC w/ W98 FE installed.

I was thinking something along the lines of ALAVASOFT's ADWATCH or SPYBOT. What do U guys think:

the program would preferebly be freeware, and MUST BE LOW ON RESOURCES since the machines are quite old (PII 350MHZ)

And when running in background when it would find some spyware the program should automaticly block access in silent. SO students won't go all crazy like HEY, what is this?

tanx in advance