Need help with my wireless connection?

I need help with my wireless connection
I have a speedtouch 780wl router and 2 desktops (one XP pro other XP Home).
1 desktop connected by Ethernet cable the other connected by a Asus Wireless card
The one connected by Ethernet connection no problem
The one connected by wireless is were the problem lies
It says that the signal strength is excellent and is connected to the network at 54mbs.
But when I try to access the internet the pages (google) takes an age to appear and it downloads at a max of 500 bytes per sec.
I’ve tried changing security from WEP to WPA did not work lost all connection
Tried switching off security didn’t work. turned routers firewall of no diffrence.

i pinged the router from the pc with wireless and it sees the routers ip.

I don’t know what to do as im quite new to wireless connections

Please can you help? If you need any more detail let me know?

I take it none of you experts no Jack
not one answer about my problem some forum this.

i kind of fixed my network. done it through messing about with it. because nobody on this forum could help me. F****rs.