I'm a computer idiot

I need step by step instructions to get rid of a virus.
what I know:
OS: windows 7
Opens IE windows with shopping adds random times.
occasional virus warning in temp?? I think I cleared all browser temp folders… also did disk clean up and it cleared temp files. any others?
virus shuts down avast in tray
not detected by avast when I scan
i have spybot S&D and it reports all clear
whats next? I need free downloads and/or easy step by step instructions. I will write down the exact virus warning next time I see it and post it.

avast antiroot says:
avast! Antirootkit, version 0.9.6
Scan started: Friday, May 14, 2010 22:19:04

Registry item [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList\S-1-5-21-1296163551-1315203272-2872040829-1000] RefCount=17 HIDDEN

Scan finished: Friday, May 14, 2010 22:29:22
Hidden files found: 0
Hidden registry items found: 1
Hidden processes found: 0
Hidden services found: 0
Hidden boot sectors found: 0

Run Malwarebytes yet? Try that if not.

Forget about Spybot… You can try MBAM, SuperAntiSpyware and possibly Hitman Pro. However, I’d suggest reinstalling your OS from scratch and re-thinking your security setup since your current one obviously failed. Antivirus alone is definitely not enough these days. And I’m not suggesting you should buy tons of products and cram them onto your PC. Start from basic things such as using a limited user account, configuring SRP or AppLocker, using sandboxed browser etc.

So, did you try any of the suggestions yet…??
Post back your results…!!!
asyn

Ok… so I downloaded Malwarebytes and ran it. I found like 6 things that Spybot had missed. It did the trick and removed whatever was messing with my system. So thanks Gargamel!!! So now please fill me in on what I should do to avoid this in the future? I’m not up to speed on any of the abbreviations you guys you so please spell it out for this poor old man. Also if you can point me to downloads and best of all free stuff I would be eternally grateful.

Cheers,
Garth

First thing I suggest is to turn User Account Control all the way up (Always notify). Go to control panel, User accounts, Change User Account Control settings.( I’ve found this setting to be more secure)

As others have said, lose Spybot and keep Malwarebytes, Spybot hasn’t been worth keeping for years.

Another program I would use is Spywareblaster. It’s free, uses no resources, and will help protect you from spyware.It works with I.E. and Firefox. Get the free version, The only difference between free and Pro is auto-update.

http://www.javacoolsoftware.com/spywareblaster.html

Ccleaner is a good program to keep your computer clean and fix registry errors, It’s also free.

http://www.filehippo.com/download_ccleaner/

Make sure to keep your programs and windows up to date. I check Malwarebytes daily and Spywareblaster weekly.

If you think there’s something on your computer and Avast and Malwarebytes isn’t finding anything, You can run a free on line scan with Nod32.

http://www.eset.com/online-scanner

Another thing, Your not a computer idiot, Your just learning, And believe me when I say we have all been there.

Cheers Marc! I’m installing right now!

No Problem, Glad to help.

thanks all for your advice. Moderator please close this thread.