Avast or AVG? Which one should I download?

I have a virus on my comp and don't know which one 2 download since I'm being told different things and I basically have only one shot at this so if it messes up my comp I cant get back online 2 fix it. Please let me know IF YOU HAVE USED EITHER OF THESE and if they worked. Which one should I pick?

Question asked at Yahoo Answers

Avast! is aimed at preventing several types of computer threats, including those that are not technically computer viruses such as spyware and even rogue anti-spyware, and can also make a virus Recovery DataBase which is used to recover files when they are infected (instead of deleting them). The program is available with text and voice translations for 27 languages.

Awards and Tests

* From Feb 2006 to June 2008, Avast has failed 3 times out of 13 times at the VB100 tests by Virus Bulletin. From 1998 to June 2008, it has failed 22 times and passed 25 times at the same test. It has failed the last two tests which were on April and June 2008. [5]
* As of July 2007, both Avast Home and Professional Editions have gotten a 6.5 out of 10 Editors rating at CNET reviews.[6]
* SC Awards 2006 Finalist
* Review Centre Award 2006 for Best Anti-Virus software.

What do you get with the AVG products?

* Trusted protection
AVG products are running on over 70 million computers worldwide.
* Easy to use software
Easy to download, install and use.
* Security with award-winning technology
High-speed automatic updates, unique Internet security technology, certified and awarded by all major independent antivirus certification companies.
* Free support
Technical support and new program upgrades included at no extra cost.