disclaimer: the following test is based on my experience and it is only an amateur one.
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IMMUNET Protect 2.0 free is easy to install, it doesn't require to reboot.
Configuring it is also very simple.
IMMUNET 2.0 free uses two antivirus engines, has a very powerful realtime module, lacks of web protection, cannot scan inside compressed files and is not able to detect and remove rootkits (some functions more are available in the Plus - paid - edition)
It requires of an internet connection in order to work properly.
I have tested it against 10 known- nevertheless dangerous - malware samples: Trojans, Keyloggers, Virus, Worm, Spyware and Exploit.
I copied 10 compressed malware samples into my VMware Player running XP Pro SP 3
When I tried to unzip the first malware sample I had been immediately alerted by IMMUNET Protect 2.0 free real time protection

As a result I had to temporarily disable Immunet Real Time module and I could extract the remaining malware samples to my desktop.

Well, now 9 infected executable lie on my desktop
.
I can run a scan

Not bad: 8 malware samples have been detected and destroyed easily.
Only a Win32.Induc.A is not detected.
I can get rid of it thanks to a-squared 4.5 free via context menu scan

Since all zipped files still contain malware samples I run an a-squared 4.5 free scan which can easily quarantine them

My opinion:
IMMUNET Protect 2.0 free has considerably improved in comparison with previous versions, it takes 20 MB memory according to my taskmanager but is still a little bit immature even if looks promising and its detection rate is quite good.
Do note: I haven't tested it against new 0 days threats.
I believe that for an advanced user might be sufficient.
My suggestion: use it along side a good antimalware (ie.SAS Pro, MalwareBytes' AntiMalware Pro, EMSISOFT Anti-malware or even Windows Defender) if you believe IMMUNET protect meets your needs and if you practice a safe surfing.
Here are some virustotal reports of some malware samples I used for my test
Code:
http://www.virustotal.com/en/analisis/274d87ef20163c99ac352385a70cd1583620a58e16f01767666a705e6ba47f91-1277767450
Code:
http://www.virustotal.com/en/analisis/adcfaac703e66eec2a6849228d05b4d4b691631201d0790db5cd603a52346d2f-1277767308
Code:
http://www.virustotal.com/en/analisis/f3dafef56f0d9be149a88dc89fcdf93e0248a1444dcc0000dd2bf68619a5f849-1277767175
Code:
http://www.virustotal.com/en/analisis/afc6422a2fa81952373fcdd60846b719e30cb85be5ad3dfb67f5b103c321ed58-1277767102
Code:
http://www.virustotal.com/en/analisis/be20a2a4ba11c576baebc09679b4c5ef94276e288ee09d2ca44ca6d9c3b51ce4-1277766961
Opinions, suggestions, corrections are welcome
Thank you