Windows 7: is 2 antivirus excessive

hi i have always used avg free. It has worked well, but was wondering whether it "cover all bases" is it good to have another anti virus aswell or will the performance hit be too great to value this. I recently have downloaded microsoft security essentials as the possible other. One of the reasons i ask is that it i trialled a different anti virus and did a scan and it found about 10- 15 threats although these could have been cookies, i then did an avg and it didn't discover these. (the trail couldn't heal as you had to pay, or something). However about a week later i did notice avg pick up the same threats leaving me to feel it dosn't fully protect the computer. If neither of these is an option does anyone have a recommendation thats 100% free.

I will give my answer and then wait for all that will disagree. The answer is yes. Just use Microsoft Security Essentials and Malwarebytes with the Windows Fire wall. That is enough if you have the last component, common sense. Without that component a dozen A/V will not be enough.
The more you use the more Ram, and the slower the computer. Use enought AV, you can even slow down the computer enough to cause HD damage
Make a system Image once a month, on an external hard drive. If you make a mistake, just use the image.

Now lets wait for the disagreement to start.

Anti-virus programs are resource hogs, they will fight for your system's resources, plus they may detect each other's definitions as a virus.

If you're happy with AVG, then keep it. Download and install Malwarebyte's Anti-Malware as an extra scanner.

There are also 'online' anti-virus scanners, so you could use one of those without installing two on your Machine.
See a list here Google

i only just installed microsoft sercurity essentials and shall wait for the sca to finish, see what it brings up and maybe uninstall it or the avg. One complaint about other av i have tried is that scan time seems to be long but the files it scans is les than avg. I think it was norton that scanned 20000 file. Yet avg scans around 500000, so what about all these other files. Why is this

Welcome jhd17 to Windows 7 Forum.

There are a lot of free AV's out there. Some are better than others

If you want you computer to be 100% free of threats then mission impossible. It is virtually impossible to keep up with all the threats, spam, hits and viruses that occur daily.

The only way NOT to get computer threats, hits or viruses is not to OWN a computer.

It is generally a bad idea to run two real-time protection antiviruses. It isn't a matter of performance. AV programs tend to interfere with each other, and cause a number of issues, including causing the computer to crash immediately after logon, having one AV mistake the other for a virus and trying to delete it, and causing both to not function properly, leaving you unprotected.

The best idea is to use a on-demand scanner such as MalwareBytes Anti-Malware free version. MBAM only runs when you start it and does not cause the problems I listed above.

Also, Microsoft Security Essentials (MSE) performs better than AVG in every test, and had earned a number of awards from independent groups since its release less than a year ago. Also, it is a proven fact that MSE and Avira AntiVir free (another good AV program) can run side-by-side without issue. I would not run AVG and MSE at the same time, as a variety of problems have been reported, including resulting networking issues and recurrent Blue Screens of Death.

ok, on thing looking at task manager that avg had about 7 or 8 processes all going this seems a bit of resource waste, but can i ask again the question of why avg scans so much vs others and thanks for the warning

Do you have MSE scanning for a full scan or quick scan?

IIRC, by default AVG does a full scan, while most others do a quick scan. I don't think this applies to your question but I will also add that AVG deletes most cookies, while many other programs do not, resulting in it reporting it removed threats when other programs do not.

Personally, I use a combo of MSE, which does a full scan at 1AM, and MBAM, which I use to scan my computer every sunday, or when anything weird happens.

it just did it automatically after install, my guess is quick so i am now doing full