I have a 2.6 Ghz computer running windows2000, but i want to install
redhat 9.0 on it and still use my wireless LAN.  My current LAN is a
belkin 802.11b but i want a card that does both 802.11b and 802.11g. 
Of course it needs to be PCI.  Also i want to make sure it is
supported and easily to configure for Linux redhat 9.0   I've read
some on the internet, and they just talk about the applicable drivers
but i want one that comes with the right driver.

When you look up the driver for Linux, it doesn't matter what brand
name is on the wireless card.  These are all made by a few companies. 
Other companies put their name on it and resell it.  The drivers are
named based on the company that manufactured the chip, not the company
that sold the chip to you.  I have an "Ambicom" brand name wi-fi card
that uses the "orinoco" driver.  I have used a "D-Link" card that also
uses the same driver.  I guess you could buy a card that you know uses
the "orinoco" driver.  I have heard that others are not as easy to use
as the "orinoco", but I don't know anything for sure.

Red Hat will autodetect it, probably.  Dont worry about it.  If you
are paranoid, download knoppix or another "live-cd" Linux
distribution.  These are bootable CD's.  You put them in the CD rom
and turn on the PC.  It doesnt touch the harddrive.  Everything is
autodetected and it loads off the CD.  You can remove the CD, reboot,
and you're back to your old windows settings.

Just make sure you have every security setting disabled at your wi-fi
access point.  That means setting up DHCP, turning off encryption,
turning off MAC address filtering.  Once you confirm that the wi-fi
works, you can worry about turning security settings back on.