What is the most light-weight ( in terms of RAM/CPU Usage) anti-virus for Windows XP?

[JamesAndersonJr]

A client of mine asked me to fix her netbook, because she felt she had many viruses on it.

Well...She was right! I found a plethora of viruses, root-kits etc. on it, and her system clock was set back to the year 2002!
Now, I've cleaned the laptop off [mostly] with a combination of Malwarebytes Anti-Malware and Avast. But the problem I'm facing is that her netbook is showing a total of 0.99 GB of RAM!

Avast has become a little bit heavy (to say the least) over the years, and has heavy marketing within the free versions. So I know, working with < 1 GB of RAM, I can't leave it on her computer.

Does anyone know of an extremely light-weight anti-virus that:

A.) works on Windows XP SP3
B.) Works well with less than a gig of RAM
C.) Has active monitoring, like Avast.

 

[Math Geek]

i was looking specifically for this same type of system. i was fixing up a bunch of old xp machines and need the lightest av i could find. after testing everything i could get my hands on, i found avast to be the lightest AV i could find that did its job fairly well. i tried many others and the light ones were not very good in what they could do.

the ads do get a bit annoying but take a look at the resources it uses. was less than 30 mb when i tested it out compared to at least 75-100 mb for other "light" programs.

it has been a year since i did this testing but i have not heard of another av taking this crown from it for being so light on resources.

 

[jimmysmitty]

XP SP3 doesn't work well alone with less than 1GB of system RAM. Adding an AV will make it even slower. The lightest weight one I know is MSE because it is so basic and does have active scanning but not as advanced as some others.

 

[geofelt]

Microsoft security essentials is unobtrusive and efficient.
I think it still works on XP.

 

[JamesAndersonJr]

Microsoft security essentials is unobtrusive and efficient.
I think it still works on XP.

Unfortunately, Microsoft has blocked MSE installs on Windows XP because of it's EOL status.

 

[geofelt]

Microsoft security essentials is unobtrusive and efficient.
I think it still works on XP.

Unfortunately, Microsoft has blocked MSE installs on Windows XP because of it's EOL status.

FWIW, I have an ancient laptop with XP PRO 32 bit installed and also Microsoft security essentials.
768mb ram.
I was able to download and update the security definitions( Last time was a year ago)
Ran a scan and found no problems.
You do get a warning in awful red numbers that the operating system is no longer supported and that your pc is at risk.
It seems though that they do still support updating MSE.

 

[xSimply1337x]

I'd say that as long as you are connected to the internet (which is how you usually get viruses anyways) you can use a cloud based antivirus. I recommend Panda Security. Here is a link to their free version of the software, however, if you really end up liking it enough I'd recommend getting one of the paid versions.

http/www.pandasecurity.com/usa/homeusers/solutions/free-antivirus/

great thing about it is that it doesn't hog any resources. it only uses a few megabytes of memory to run the client that connects you to the cloud based anti virus system. so all you need is an active internet connection.

--EDIT--
the free version is anti-virus only and has limited real-time protection when browsing the web. If you'd like to reduce you're chances of getting a virus when browsing then I recommend installing the Adblock Plus addon/extension on either Firefox or Chrome.