Disabling encryption on your router or testing out the IPAQ on a free network, will allow you to troubleshoot what could be causing the problem. Right now there are many variables at play and any one or multiple variables could be contributing to your problem.
So, the first thing to do is see if you can connect to a free wifi hotspot.
If you are able to connect to a free wifi hotspot, then test on your network, with the security disabled.
If you are able to connect to your network with no security, turn security back on
You might also review these articles that are posted on my blog (which features the IPAQ hw6925 by the way) here:
How do I connect my Pocket PC to the Internet?
Connect your Pocket PC to a WIFI Access Point