Do not install it under any circumstances nor purchase it. You don't need it nor want it.
In general you should ignore any popup ads from anywhere on the Internet telling you your computer has malware and needs to be checked. These are strictly for PCs, not Macs.
Helpful Links Regarding Malware Protection
An excellent link to read is Tom Reed's Mac Malware Guide.
Also, visit The XLab FAQs and read Detecting and avoiding malware and spyware.
If you require anti-virus protection I recommend using ClamXav.
In General 3rd Party AV Software is Not Required as Mac OS X tends to look after itself.
Read Here > Antivirus Discussion
To keep your Mac Happy... See Here...
go into your router, add a keyword or the adserver and you can filter and block those pop-ups.
Turning off all pop-ups would be nice, but it interferes with too many sites. Odd because when I run Windows I don't - they know I am not using an OS X browser, IE 9 and the others seem to handle (block) and allow more fine tuning of alerts and pop-ups.
I think the router's firewall log section is useful though.