Its not clear what wireless client software you are running on your laptop, which you would like to change for Windows XP's bundled Zero Config wireless functionality.
Whichever it is, remove via Add/Remove Programs.
Then right mouse click on "Wireless Networks" in "Network Connections", and choose properties.
Then add a "Preferred Network", using the settings for your WiFi network;
SSID, WPA/WEP encryption, Passphrase, etc.
However, there will probably not be a noticeable performance gain for your Online Gaming.
Data traffic latency rather then bandwidth/signal strength is more important for gaming (& VoIP).
The less layers there are, the better.
But that would mean stripping off WPA/WEP security, removing software firewalls such as Norton, McAfee, ZoneAlarm, etc.
Which you probably don't want to do for your laptop.
Gaming platforms are often connected via an Ethernet cable, as well as placed in a DMZ ("De Militarised Zone") to bypass the router's hardware firewall, to remove as many causes of increased data latency.