Hmm, it sounds like the local side of things is working. To verify that you can open command prompt on your PC and run the command "ping 192.168.0.100 -t" (without the quotes) Then try to connect to wifi with your DS. It'll say "Request timed out." until the DS connects, so don't get too worried about that. Once the DS is connected it should start to reply (ex. Reply from 192.168.0.100: bytes=32 time=4ms TTL=127). This test will verify the connection between the DS and the dongle, as well as the encryption settings being set up right.
I have a feeling the problem is either a routing problem, or a DNS or Default gateway address problem. Could you post the settings of your "Intel PRO/100 VE Network Connection" which can be found by using the command "ipconfig /all" in command prompt. (The ones I'm interested in are IP Address, Subnet Mask, Default Gateway, DNS Servers)