Here is a List of FREE Online Scans that target Viruses and Spyware:

Trend Micro - Free online virus Scan
HouseCall is a Free Scanner that can Scan Your PC for the latest viruses and remove them automatically and or help you with instructions to remove them manually if necessary.

BitDefender Free Online Virus Scan
BitDefender Online Scanner is a fully functional antivirus product, featuring all required elements for thorough antivirus scanning and effective cleaning.  Bitdefender scans your system's memory, all files, folders and drives' boot sectors, providing you with the option to automatically clean the infected files. 

Panda ActiveScan
Free online antivirus to combat viruses, spyware and other Internet threats.  They scan for and remove over 110,000 viruses, worms and Trojans from all system devices, hard disks, compressed file and all your email.   They also detect spyware and the following types of malware: Dialers, Hacking tools, Jokes, Security risks.

Free Online Virus Scanner by Kaspersky Lab Antivirus Software
The Kaspersky Online Scanner uses Microsoft ActiveX technologies to scan your computer for malicious code. The scanner uses MS Internet Explorer to scan your machine while online.

eTrust Antivirus Web Scanner
Free Virus Scan · Cleaning Utilities · Virus Information Center - The Virus Information Center serves as a rich, up-to-the-minute resource, containing detailed information on viruses, worms, Trojans, and hoaxes, as well as valuable documentation on the implementation of comprehensive antivirus protection. CA’s eTrust Threat Analysis and Response Global Emergency Team (TARGET) monitor around-the-clock to defend against the damaging effects a virus outbreak could cause.

X-Cleaner Micro Edition
This online scanner was developed by FaceTime Security Labs, makers of the X-Cleaner Spyware Remover. X-Cleaner scans for a wide range of Greynet Applications including: adware, keyloggers, Trojans and many other forms of potentially unwanted software that the downloadable freeware version of X-Cleaner also targets.

Using Housecall to scan for Viruses

1. Open Internet Explorer and type into the Address Bar http://housecall.trendmicro.com and press Enter.    (You can also click on the previous link if you so choose).
     

2. Under "Scan Your PC" click on the link that says "Scan Now. It's Free! ".
     

3. At “Please Select Your Location”, click on the Drop Box, select United States and click on the Go button.
     

4. Housecall will then begin downloading the updates onto your computer. This may take a while to finish but once it's finished it will show you the drives you can scan on your computer.
     

5. You'll want to put a checkmark in the box in front of the Local Disk (C:) and then click the "SCAN" button    to the right. This will open another window showing you the amount of files scanned and below that a list of    all the viruses it detects. The scan may take a while to run depending on how many files are on your computer.
     

6. Once the scan finishes you'll want to select all of the viruses it detects and then click on the "Clean" button.    Any files that Housecall is unable to clean you'll then want to click on the Delete button and try removing them from the computer. Once that finishes click on the "Close" button. It will bring up another window asking if you really want to close. Click on "Yes" and it will bring you back to the main page.

Remember: If you do not feel confident in your ability to accurately follow these instructions, please do not attempt to remove a virus on your own.