No. I was not saying that.
The only way to make that change, or to unshare an admin share,
is with an admin account. Hence, I question if we are speaking about
the same thing, or whether your account really is a plain limited user
account (note that many accounts, not just "the Admin" more correctly
named Administrator in the default, can be admin accounts).
Using the registry to set the LanmanServer keys has effect no matter
who is logged in, or for that matter even if no one is.
If your roommate does not have an account on your machine then
there will be no access to the admin shares. There may be access
to other shares if you have defined some. If you are using Simplified
Sharing mode (or have Home which forces you to do so) then if the
Guest account is enabled for network login, or if you have given the
roommate an account on your machine (even if not an admin account)
there is possiblility of access.
If you do not want to share out while connected with wireless, then
locate the network connectoid for your wireless adapter in the networking
applet, right click on it and select its properties and therein uncheck
File and Print Sharing for MS Networks in the drop box.
Also, or just, turn on the firewall without exemptions for the wireless
interface.