If your computer is infected with something...

Get Rid Of Trojans
1) Turn your firewall on!
2) unplug the connection to the internet - this will stop anything that is taking commands from someone/thing over the network/internet
3) run hijack this a couple of times and see if there is something that keeps coming back or if something shows up the second time
4) delete folders in c:/program files that are obviously not welcomed software
5) if I am unable to delete certain folders, I try:
----hold down control then click & drag the folder to the trash
----restart and go to c:/program files as fast as possible and try to delete the program before it starts running

Get Rid of Viruses
6) The more virus definitions the better. On another computer, download 2 other top Anti-Virus software trials as well as the most recent version of the company you are currently using and put on a CD/ jumpdrive.
----McAfee Virus Scan Plus
----AVG Anti-Virus Free Edition
----Norton 360 Free Download
7) Install, restart, update definitions, and run a scan from each of the other virus software. One at a time. You will have to plug into the internet to install them. Install the company your using last because it will require you to uninstall your version first.
8) The software should be catching and removing most of your problems. If I keep getting problems I go back to step one and keep working my way down.

Get Rid of Spyware
9) Install one of the Spyware and Adware Protection and Removal Tools listed here:
----Windows Defender
----Trend Micro Antispyware 3

Resolution?
*If you still have issues but finally can get on the internet, use recommended free virus scanning services. They are opportunities to find more definitions that may have not been updated by your software.
*If you still have issues and have patiently and successfully installed and updated definitions on 3 of the top anti-virus programs, and a couple of anti-spyware programs, you could have someone take a look at your hijack this results for anything that was hard to recognize yourself. There are sites and resources to look up what is bad and good but most likely you are not in a position to do internet research.

Stay Current!!!
10) update windows
11) update your anti-virus and anti-spyware protection
Make sure your definitions are set to auto update. Make sure you are set up to scan in real time as well as a full system scan on a regular basis once or twice a week to start. Make sure you will always stay protected and don't let your definitions skip updating or all your trials expire. It's good to have one annual current subscription as well as using trials through out the year to double check your software. At the end of the year, you might prefer a different software that's easier and doesn't slow down your computer as much.

TOO Slow?
Once you recover, your computer will slow down from running 3 anti-virus programs unless your computer has a really fast processor and a lot of memory. Decide what Anti-Virus program you would like to use and invest in purchasing the most recent version. Search Download.com for "anti-virus" and you can see the ratings to help you choose.

What you should have installed:
NOW: hijack this, 3 anti-virus programs, 1-2 current anti-spyware programs, and your firewall should be turned on
Once you feel safe: hijack this, 2 anti-virus programs, 1 current anti-spyware program, and your firewall should be turned on
Wait a couple of days or a week before going down to this if you really need to otherwise stay with what you have: hijack this, 1 anti-virus program, 1 current anti-spyware program, and your firewall should be turned on
Once a month: try a virus scan tool that doesn't need to stay running
Once every couple of months: install a trial of a top company to see what your software might be missing

Resources:
Protect Your Computer