Firewall/Anti-Virus Programs for Netbooks

Does anyone have any suggestions for firewall and anti-virus programs that would work well with netbooks?

I'm searching for really resource-light programs that won't effect system speed too much and still work great with Windows XP.

 

i use pctools firewall, i dont think it has alot of impact on performance
http://majorgeeks.com/PC_Tools_Firewall_Plus_d5470.html

also, microsoft security essentials is a decent antivirus program, again without much of a performance hit.
http://www.microsoft.com/security_essentials/

 

I use Comodo Internet Security on my 5 yr. old laptop running Windows XP.