Linksys/vonage = problems

We switched to vonage a few months ago and at first everything was ok. Now nearly every call is dropped. I spoke with customer service and was told I need to encrypt my wireless router.

I changed the password and ssid. I changed it to disable the ssid broadcast, but changed it back since it seemed to fubar everything.

My problem is this. My daughter and I both have laptops that run vista. We connect with no problem. My husband has a dell desktop that runs windows xp and I can't get him connected to save my life. How can I fix his computer? I've tried everything. I had a text conversation with linksys customer service. She knew less than I do. I was pretty stunned by how useless that conversation was.

Can someone help me? Does anyone else have trouble with Vonage?

Thanks.