i have the free version, and it most definitely scans my downloads.

I just debugged a BADLY infected computer with three pieces of software.
To begin with the computer was infected with Home Antivirus 2010.
After managing to finally force it to not start up immediately using msconfig in the <run> program prompt in the start menu I was able to begin.

I used a disk to copy Firefox over to the computer because internet explorer was FUQUED! I down loaded Avast to the computer.

I had to uninstall all the anti Virus and reinstall Avast. It had Avast and it was buggered up viciously. Connecting to the internet was nothing but redirection and prompts that the computer was infected.

After reinstalling Avast I ran a boot sector scan after rebooting and deleted every file it came across. 16 total, three Rook Kit infections, two viruses, the rest were Trojans. Now I managed to dent it but it was not over. I installed and ran Spybot Search and Destroy and found 154 additional trojan, malware, security breach, and dataminer infections.

I then installed and ran CCLeaner and immediately went to the tool/startup and looked for any traces left from other Trojans and found two. I then did a registry scan.

Now the computer is all Bueno! I get to show its owner what some real computer know how can do! Someone else tried to fix the computer and thankfully didn't screw anything up. Best is that they get full protection configured for them. All they have to do is manually scan once every two weeks and all will remain golden!

Home Antivirus 2010 is Extortionware that will saturate your machine with all kinds of crap. Getting rid of it is complicated but my answer is a little time consuming but works! the tough part was getting the malware to shut off long enough for me to eliminate it a piece at a time.

Between these three pieces of software you can keep XP working under a lot of circumstances!

Lesson for the owner, if an internet pop up says your computer is infected FREAKING IGNORE IT! If you are not notified by installed software like Avast or Spybot it is an attack in disguise!

Cheers!

Extortionware - I've been calling it ransomeware, lol.

I have been recommending Avira to my friends and clients.
A great resource for extensive unbiased information about anti-virus programs is av-comparatives.org.

I have tried and tested just about ALL anti virus and out of all I'd recommend either Avira free, Microsoft security essentials (which you can still download at softpedia.com) I use MSE on my windows 7 and it works great as far as detection and removal. On vista I use Avira Premium.

If you want more than just anti virus protection I have 2 remaining free license keys to Online Armor firewall (I got them through a previous promotion)

AVG USED to be geat, but now it's sucks. Low detection and high cpu usage!!

So other than Avira and MSE also give PC Tools antivirus a try as well as AVAST personal home edition.

good luck in your search.