System Tools

Find your IP Address

Check Internet speed - then click the Speed Test icon on the bottom of the screen

AntiVirus Software

Symantec AntiVirus definition updates For your installed Symantec AntiVirus program - updated almost daily with new definition files.
McAfee definition updates For your installed McAfee VirusScan program - updated almost daily with new definition files.
   
Trend Micro's Housecall Free on-line virus scan
McAfee's FreeScan Free on-line virus scan
Symantec Security Check Free on-line scan for general system security and virus
Panda ActiveScan Free on-line virus scan
   
Grisoft's AVG 7.5 software Free, installable antivirus scanner
   

Hard Drive Utilities

HDD Health v2.1 Build 159 Utility that monitors the SMART status of drives and predicts a failure date.
   

Spyware Removers

Ad-Aware SE Personal Free - My first choice for spyware and adware removal
SpyBot Search & Destroy Free - Another great spyware removal application
   
   
   

Registry Cleaners

IOLO System Mechanic Try the free 30-day trial, very good!