Hello,
I am trying to change the orinoco driver to the HostAP driver.
my orinoco driver wireless card was under eth0, so I made wlan0 to work as my HostAP driver for my wireless card.
And I got this far:
I installed the HostAP driver, I added wlan0 to the /etc/modprobe.conf this:
alias wlan0 hostap_pci
I also copied the ifcfg-eth0 to ifcfg-wlan0 and changed the device variable to
DEVICE=wlan0
in the /etc/sysconfig/networking/devices folder, and did the same thing in the /etc/sysconfig/network-scripts folder (copied and renamed the device).

After a reboot, when I use ifconfig up wlan0 it gives me this:
wlan0: Unknown host
ifconfig: `--help' gives usage information.
When I use ifup wlan0 it give sme this:
hostap_pci device wlan0 does not seem to be present, delaying initialization.

my lsmod output is this:
hostap_pci 65808 0
hostap 144008 1 hostap_pci
sis900 24064 0
mii 6016 1 sis900
orinoco_pci 8576 0
orinoco 60820 1 orinoco_pci
hermes 7808 2 orinoco_pci,orinoco

ANY help would be appreciated, thanks!!

I think the HostAP driver is only for Prism2/2.5/3 chipsets. I'm not sure it works with orinocos.

It's Prism 2.5
lspci:
00:06.0 Network controller: Intersil Corporation Prism 2.5 Wavelan chipset (rev 01)

oricono works ok but lacks a lot of features, people seem to like HostAP

how can I disable the other one?

Look in /etc/modules.autoload.d/kernel-2.6 and remove any references to the orinoco drivers. The file location may be slightly different on your system, but on mine, it's in there.