Wireless Problems

I have an HP Pavilion dv9429us laptop with Vista installed, using a Broadcom
4321 AG adapter and the Verizon FIOS provided Actiontec M1424WR router.
Since I bought the computer, I have had nothing but difficulty with internet
connections (limited/no access, periods of good connectivity followed
randomly by inability to detect wireless networks, etc.). Despite reboots,
altering the adapter, etc, there is no consistent solution. My other XP
laptop never has no problem with connections. I have read hundreds of
strings for help, none of which seem to work. I am about to buy XP for this
computer, but thought I would check one last time to see if anyone can help
with the problem. I am extremely disappointed with Microsoft for such a huge
problem, and cannot believe there is not an easy fix or patch. Thanks for
your help.