Trying to reduce my lag in TF2

Your internet sucks.
:|

That's AT&T for you. I don't pay for it, my parents do, so I'll take it for free, but still. :/

How far away from your router are you? My Internet is like 400 KBPS. I run TF2 no lag most of the time. I do have a core i7 and 6 gb of ram, but I think it's the internets fault.
You could have a b/g/n wireless card and a b/g/n router but yours could be like mine where if one person is using b or g, it slows the entire network down to b or g. That's probably it...

That could be, as usually someone is always on another computer or streaming netflix to one of the TVs. There's a total of 4 computers in my house (my laptop and one other, and 2 desktops).

And the router is right on the other side of my wall. Like this:
router||my room
With the || being the wall between them.