[cuteperv]

Dude first I need to know which equipments you have first. Cause we have 3 networking standard and each of them are different. Pick the 1 that you currently using then follow with it
Standard 1: wireless to wireles
standard 2: wireless to a router, then router to ethernet
standard 3: ethernet to ethernet.

I think ur using the wrong standard here. Since your router is a wireless router, you only need to connect your tower to the internet by using an ethernet cord plug directly into that wireless router. Then through that wireless router, connect your laptop to it by whichever wireless standard ur using.
In order for your laptop to talk to your tower by passing through that wireless router, simply do a networking wizzard in Windows XP. Before you do this, make sure you do the following
1) Turn of all firewall
2) turn of all antivirus
3) If ur using SP2, disable all XP SP2 firewall

Now do the following:
1) Start menu/control panel/network connection
2) double click on network set up wizzard.
3) a screen comes up, click next, next again. Now this screen is confusing. XP asks u how u network your laptop, i suppose you have an integrated LAN NIC on ur laptop. Ignore it, click on the wireless card one, then check the box says "ignore disconnected ..." CLick next
4) On this screen, choose the option where it says this computer connect through another computer in order to go to the internet. click that. click next
5) Click next
6) The next several screens u can do it yourself.

After u finish all of the steps. Do the same thing on the desktop.
If you do it right,you will see that XP enable an Internet Gateway called Internet Connection Sharing in control panel/network connection.
Now ur laptop n desktop can talk to each other.