I'm sorry to hear you're having this kind of problems. Perhaps something
related to WEP?

Anyway, if not that, I have to say I had a bad experience with Sandisk wi-fi
cards. I ended up returning it and buying a h4150 to replace my h3970. Sad,
I know.

Lex,

A couple of things you can do here so let's start by isolating some of the
components to see where the problem is.

On your D-Link, go to the configuration page and insure you have first
configured the router for no security (this should not be your permanent
state, but you want to insure your ppc can connect before locking things
down)

Also if you have the ability to view connected devices go to that page of
the router configuration and watch it to see if you can see your PPC when it
attempts to connect.  Be sure you make note of the SSID the router is using
for the next step (your router documentation should explain about the SSID
and where it is located)

On your PPC.
Go to your configuration for the adapter and insure no security is enabled
(no WEP, no encryption). Enter the SSID for your D-Link and save the changed
configuration.

If you have a WiFi Utility loaded on the PPC start it and check to see if
the card is working properly. If it is you should be able to see available
networks. They will be designated by their SSID.

If you are running WM 2003 when the card is configured you will get a pop-up
advising you of an unsecured network and prompting you to for permission to
connect. If this not occur you should check the configuration again.

Part 2
To connect to the Internet the PPC needs to be assigned an IP address.
Either you can do this manually (painful unless you know IP) or dynamically
using DHCP. Most routers will function as DHCP servers so this should be
enabled on your router with a limited range of IP addresses. You might
consider using the same range of IP addresses as you use for your home
network (but reserving one or two for the wireless segment).

Consult the manual for your router for information about how to set DHCP up
if you've not already done so.

On the PPC if you've connected to the WiFi network check to insure you've
gotten the DHCP information you need to communicate. This should match the
range of IP addresses you entered in the router.

HTH