Something like 3/4 or more of 360s made within the first year red ring... they know this is there fault an unacceptable to they've offered extended waranties to everybody who bought one before a certain date... no bother you just send it off for free and they'll give you a new one.

You buy second hand you won't get that and there is a high chance that it'll red ring on you and be completely fucked.

They used the wrong type of solder on the circuits during the first year of production and they go brittle from the heat. Also the newer 360s have a proper HDMI output... not just component cables so they look very slightly better if you have the right TV.

If you can't get a new one make sure you get proof of how old the console is