Muddiest Point--Week Six (revised)

So I do have a muddiest point after all--well, maybe not a muddiest point but rather a cry for help.  My family bought a new computer in August.  It did not come with a wireless model installed, so we bought and installed one we thought would be compatible with Windows 7.  We are not experiencing success.  We can connect with the phone line (I should have mentioned this was DSL,) but that requires a 20 foot cable running from the kitchen to the computer in the next room.  Does anyone have a suggestion?  I've contacted our internet provider (Frontier,) and after multiple attempts to fix, it seems like the problem is with the modem.  Thank you in advance for your help.