Here are some optimization tips to use minimum resources:

first of all remove all extra background services. This can be dont through (for XP only):

TIP 1:
going to RUN in start menu. type MSCONFIG goto startup tab and uncheck everything except for some special background service u need like antivirus software or sound device manager etc. usually all other options are either software registration options, update checks or simple 3rd party softwares which choke bandwdth and compromise security (usually when u install kazaa or view too many pr0n sites
)

TIP2:
in the same MSCONFIG window goto services and check HIDE ALL MICROSOFT SERVICES. This will basically show u all the services with other programmes are running. once again there can be some harmfull service running. i have a total of 8 out of which all are unchecked except my firewall.

TIP3:
ALLLWAYS keep a firewall on your system. because...WCALL is not that safe. and if u are on the net 24 hours then its never safe anyways because of open ports and security bugs in WINXP. i am currently using SYGATE PERSONAL FIREWALL PRO. also it gives control to u abt which programme should access net or not. because programmes have a habit of doing it on their own esp NOTRON !

TIP4:
regularly scan your PC for worms backdoors etc. programmes like AD-AWARE are a good way to check for registry and browser hacks (esp if u browse too much ****
)

TIP5:
its good to have an anti-virus but frankly speaking i am not satisfied with NOTRON or any other. therefore i am surviving on my firewall and ad-aware. if u know a good ANTI-VIRUS do let me know which one is effective.