For most people, iOS 3.2.1 resolved pretty much all of the known WiFi issues with the iPad. Some people reported no difference, but most of the people I talked to said their WiFi connectivity was improved.
What I generally advise people to do is go to a place with free WiFi like McDonalds or Starbucks or Panera Bread and see what kind of connection you get there. If you seem to get a solid WiFi connection somewhere else, this could indicate an issue with your router at home.
And even though your 90 days of free phone support has expired, your iPad is still under warranty. You should take it to where you bought it or to an Apple store and see what they have to say about it.