Someone recommend some GOOD antivirus programs.
They can be very expensive as well, does not matter. They should be very good and effective.
Kaspersky Labs Antivirus
NOD32
F-Secure Antivirus
In terms of protection, you won’t find many which are better.
Kaspersky AV personal edition…
but in terms of a AV using less system resources then NOD32.
I’ve got Kaspersky, I think I should start using it then. 
kaspersky was one of the best AV i used b4 it strted hoggin on my resources…
now i use AVG free thts also good enough..
Kaspersky Personal Pro.
But yes..the recent versions do hog some resources.
Nod is very light but isnt the best when it comes to detection.
Ouch, the last thing I need now is a resource hogger.
I am too on P III 1.0 GHz, 128 MB SDRAM, Windows XP and I am using Kaspersky Personal and Kerio Personal Firewall, I enable real time protection, only when I am online, I have not performed “Full System Scan” for last two months or so, My PC is working fine.
F-Secure, Mcafee Enterprise Edition [90-day Trial Available] are other antivirus worth to Try.
use AVG free edition man, why commit a crime by using a pirated one when the same job can be done using a free one, if not better 
am using it personally and is very light on resources
@avtar KAV isnt what you would call a resource hogger.But it uses about 20mb now instead of somethinglike 8-10mb which it used to use while it was in v4.
I too will vote for AVG… Good AV Software and low on resource hogging…
Am i the only one using norton ?? (Ver 2002) on a xp sp2 machine.
Tried versions 2003, 2004, but finally went back to 2002.
Never betrayed my trust, till now.
And 2002 is less resource hugging than later versions too.
My vote goes to norton 2002.
If resource usage is important to you, consider the following three -
AVG Free edition
Antivir PE
Avast home edition
All these three are free antivirii. A good commercial one which is light on the system is NOD32.
I have been using AVG for years and have never had a problem with it.
My vote goes for Kaspersky Personal Pro, I switched over from Norton. Kaspersky is much better than Norton both in detecting viruses n in usage of system resources.
Norton is a definite NO NO .
It hogs resources and has a lower detection rate as compared to Kaspersky.
The best freeware AV is Avaast.
As Ujjwal says , the best AV which uses less sytem resource is NOD32!
But detection wise kaspersky rulezzz.
Well I’m having problems with the license keys of Kaspersky.
And as for AVG, it keeps crashing on my system.
^^ problems? Well it’s not free and u need to buy the license to use kaspersky…
Have you tried Avast! Home Edition ? Its free and has a very good rateing.
BTW an anti virus program is not just enough protection. I run a anti trojan program called A-Squared (a2) as well.