It's always good to have yet another anti virus tool in your arsenal. No matter how good a anti virus software is, it can never have 100% detection and removal rates. Having multiple tools on-hand to deal with unexpected events is a good thing.
Avira Rescue System initial boot screen
So here's Avira's AntiVir Rescue System. It's similar to the Kaspersky's Rescue CD I blogged recently in that it's also a Linux LiveCD. Avira updates their LiveCD image every few hours which is good. Unlike Kaspersky's Rescue CD you won't have to download large amounts of updates online. The downside is, of course, you'll have to download this >200MB ISO image and burn a copy to disc quite frequently if you want to have the latest updates ready in case there's no Internet where you're using it.
Updates are just a few clicks away. Depending on how old the image you downloaded is, there may or may not be any updates at all. Freshly downloaded ISO images are best but that may be asking for too much if Avira updates it every few hours. I'd just download an fresh image once every few weeks at most. I very rarely make use of this since my usual formula rarely lets me down.
Avira virus scan in progress
Scanning is also a simple click away. Avira automatically disinfects detected virus files, or renames them if it can't disinfect. This is in contrast to Karspersky's approach which typically requires manual intervention.