On my lap top running XP Pro SP2(old IBM Thinkpad T21 w\P IIIm 1GHz, maxed at 512MB of PC 100 RAM) I currently run in real time ZA Pro 4.5.594.000, BOClean 4.22.002, SpywareBlaster, Sandboxie for walking on the "Darkside" , Also Firefox 22.214.171.124 with NoScript. For on demand along with a couple anti-spyware apps. (mostly count on BOClean to stop the bad guys before they even get a foothold) I run mwavscan free (Kaspersky engine). What I am trying to decide is if I want to add a real time AV scan and\or a Internet\download scanner. Comments, suggestions on "free" choices appreciated.