Just wondering if anyone can answer a few questions.

Basically what I want to do is connect two 360's together over the internet for multiplayer gaming but without XBox Live Gold accounts.

Ive read a bit about Xlink which looks pretty good but cant figure out the full extent of what it will allow us to do. Are you able to use in game chat to speak to each other? also what kind of games are supported with this? Does there have to be a networking / system link mode on the game to play this? If so does this mean you can play games like GTA4?

Cheers

No , GTA is not supported by Xlink Kai .
Only system link Games .
BTW , you can check it on the cover of the game . When it supports system link , then it supports Xlink Kai .

the other issue you will face is the ping. If this info is wrong then please let me know but from my understanding, the reason that Kai is rarely used is that there is a ping limit (speed of data transfer) over the system link component.

As sys link was designed for playing two consoles within the same house... the distance that the data travels over the internet decreases the speed of transfer and will not allow the sys link function.

I am a huge fan of Kai and spent many hours on it with XBOX1. Unfortunately, hard to use now as you would have to have a good connection and live quite close to someone to play... Look into it though, just some heads up.