u dont need that fast of a laptop. something decent. all you really need are the utilities that will secure the network. all of which u can buy or obtain free ones.
if u will be running lots of programs from the class, try getting a good hdd. good memory. possibly 512 or 1gb if u prefer. cpu, up to u if u know your computer parts, i dont know much about cpu so i can't comment. however, i'd prefer like a pentium M for the mobility and longer battery usage.