wireless connection won't disconnect.

Hello,

This may be a very stupid problem, but it's driving quite a few of us nuts.  I have a Dimension 4600 and an Inspiron 9100 that I have networked in my home.  I run Windows XP pro.  I have a dial-up connection with a local provider.  I have no problem connecting to the internet using the wireless setup on the Inspiron.  The problem I have is getting OFF the internet.  This is how it appears to occur.  I open up the Inspiron, power it on and the Dimension automatically connects to the internet with no action from me on the Inspiron - ie I do not click on anything at all on the Inspiron , but the Dimension connects to the internet anyway.  OK, then  I can use the internet or not, but when I want to close down the internet connection, I must physically go to the desktop to disconnect it.  Nothing I do on the Inspiron will cause the Dimension to disconnect.  Time will not cause the Dimension to disconnect.  I have been told that the connection will drop automatically after 20 minutes without use.  I have also been told that a dial-up connection will NOT disconnect after 20 minutes without use and that it shouldn't.  So I am confused.  Question one - is the Dimension supposed to initiate internet connection as soon as the Inspiron is turned on?  Question two - Is the Dimension supposed to remain connected to the internet until I manually disconnect it?  If I just want to play a few games on the Inspiron, I don't need to be connected to the internet and don't want my phone line tied up.  Should going wireless be this difficult?

Thank you for any help you can give.