ASP.NET partial page upload without Updatepanel /With jQuery

I have an ASPX page .In the Top i am displaying 5 categories (Ex : Pen,Book,Shoe,Mobile,Mirror)
When i click on any of the categories,I want to show the products under that category below the header. I dont want to reload the entire page for this.I want to maintain my page as it is (The header,footer and side panels would ) when a click happens except the center place of the image (may be a DIV or Table to show Product). Whats the best way to do this ?.I dont want to go for the ASP.NET Ajax update panel.I am already using jQuery in my project.So is there anyway to do this with jQuery ? Please advice .Thanks in advance

ASP.NET Fire and Forget (One Way) Web Service

I’ve create a regular old ASMX web service in ASP.NET and added SoapDocumentMethod(OneWay = true)] to the function call as I’ve read this is supposed to make the call Asynchronous. However I call this in my code and it definitely does not make the call asynchronous, my page just sits there waiting for the function to finish working. What gives?

.NET Session not working

This is a weird one, but hopefully someone can give me an idea here. I’m putting a few values into session in the Session_Start of the Global.asax in my app. Immediately after the Session_Start my base page’s OnInit gets called and tries to use one of those Session variables.