How do I connect d-link rx with an embarq 660 for xbox 360 or do I need both, beacause it won't work without the main box which is the embarq660. Please help? Thanks

Yes the 660 is a DSL Router/Modem and it is required to translate the DSL telephone signal to the Eithernet Signal that all your compturs and devices that use the internet understand. Now I'm not sure if the Xbox requires port fowarding as that is more involved and also requies knowing what ports require fowarding. If you know or find out it does require port fowarding, then I would recomed you bridge your 660 to your D-link and call d-link to have them explain how to set up port fowarding on their router. As from personal experence the only relible way to port forward on the 660's is to bridge them to a router. If port fowaring is not required then the dlink is optional, but the 660 is required. If you are going to bridge the modem then the dlink (or other router) is required unless the xbox is going to be the ONLY thing using the connection.
To swich the modem into bridge mode requires a comptuer, (though not a dsl connection though is recomended) what you do is on the computer connected to the modem bring up the internet and in the address bar go to "http://192.168.2.1" this must be done in the address bar! Put it anyplace else and you will get pages talking about what to do once you get to that page but not to the page your trying to get to.
If you did that part right you'll get to a "Welcome to your modem configuration" page and a login prompt. The password by default is "1234" it'll ask if you wanta change the password then if you want to replace a certificate you can hit the ignore button on bouth windows. Now depending on weather you got a 660R or a 660HW the screens are a little different from her eon out (the HW has an attena sticking out the back the R doesn't) on the R you go the "Maitaince" section then to "Diagnostics" then to "Network Layer" then down at the bottom is a button "Change to Bridge mode" hit that and in a few moments it'll say it's in bridge mode and your done and can slap your router in, and you should be good unless you need port fowarding as this is only part of what needs to be done to prepare to forward the ports.
If you have a 660HW the Screens are "Advanced Setup" > "Maitanace" > "Diagnostics" then at the bottom of that page you'll see the "Change to Bridge mode" button click it and again it'll tell you when it's current mode is set right. One last word of warning while the modem is in bridge mode the number of devices connected to the modem at any point in time can not be greater then the number of ip addresses you are getting from CenturyLink (aka Embarq) if you are not paying extra for static ip address then you only get one Dynamic Ip address. So thusly can only have one device pluged in at a time.

Explain how your system is setup. Do you have the phone cord going into the 660 then the D-Link hooked to that?

P.S. Xbox's do not require port forwarding!