Vista wifi bridged to xp ethernet

Hey guys I've Tried everything to get this working hopefully someone here can help me.

I play wow and usually i just bridge the wifi from my gf's Vista labtop to my XP desktop using ethernet... I didn't have a wireless card at the time and cant run a network cable upstairs.

So heres my problem:

when i play wow on my own wireless PCI card i lagg out horrably, but i can serf the net fine and everything else.

However, when i bridge the wifi from my gf's vista labtop i get a perfect connection, even when shes playing it on her labtop at the same time.

why is it that i lagg out on my own wifi? i have tried changing the routers broadcast channel, the encryption. i have updated the network cards drivers and altered settings but still no luck, I'm utterly confused.

what could be causing me to get 2k+ latency on wow, but when I'm bridged from the labtop i get 50ms stable and never lagg

ooh btw, i have a netcore wireless 54g pci card (model NW320) its a cheap thing... with a SMC router (provided by rogers), i know the routers fine (basing on the fact that the labtop never laggs or drops out)

i could really use some help guys i don't want to bridge forever