you misunderstand (I think)
you're only disabling the wireless connection on YOUR pc
if you go to network connections (control panel)
right click the wireless network icon the first option is disable (on this computer)
Once your network is established then to connect .... same again ... but enable.
http://www.microsoft.com/windowsxp/using/netwo rking/expert/crawford_02april22.mspx
if you want to get tekkie
the problem lies in winsock .... when it initialises it looks to the gateway ... it's not fussy ... any gateway will do.
if for some reason your adsl blips - because network timeouts are so long ... you rarely see an error message saying that your adsl isn't there .... so from your point of view all is well .... however winsock has latched on to the first available ...... which is the wlan.
you say it's not a problem having two networks connected - phsically you are right .... it's not a problem
but topologicaly it IS a problem windows networking expects ONE internet connection on port 80 .... so giving it two just isn't an option ... it just latches on to the first it finds.
If you want a propper multilan setup ... correctly bridged with load balancing to ensure you always catch the "right" gateway ... you are talking serious money
if you are willing to bodge ... it's free