Recycle your old computer and equipment (free local pickup)
scrapcomputer.com

Internet Performance Test
DSL Reports Speed Test - See how fast your cable modem moves data

Help with Windows
Bleeping Computer - Excellent resource for computer help and new viruses/spyware
TweakXP.com - Resources on correcting Windows issues and speeding up Windows
Microsoft Support - Official Microsoft Help and Support

Privacy and Network Scanners
DSL Reports Port Scan Tool - Test if your network has ports open to internet attacks
CA's eTrust Tools - Some useful tools such as registry scanner, privacy scanner, etc.
CA's eTrust Pestscan Web Scanner Tool - On-line scan for viruses and spyware
Trend Micro's Online Virus Scan - On-line virus scanner