Keyboard lag + touchpad going crazy

I've been having this issue on my XPS M1530 for the past month or so but it's gotten worse now...

Sometimes (well, most of the time now) if I touch the touchpad at all it will just jump around everywhere and start clicking on random things, usually at the edges of my screen (and yeah it closes my windows). Once it stops I usually won't be able to click for a bit and have to keep pressing both the mouse buttons to get them to work again.

I've recently reformatted and I still have the same problem, except (I didn't install the Dell drivers yet when this happened) when I press the mouse buttons then it'll cause the cursor to move in a straight line to the right, or sometimes up. Usually I just use a USB mouse now and disable the touchpad, but that's not exactly convenient when I want to put the laptop on my lap.

Another issue I'm having is the keyboard missing letters and just lagging in general - you have no idea how much of a pain this was to type. It doesn't happen all the time though, maybe about a third of the time it'll work properly and then just randomly start skipping letters again.

Also, the media buttons up at the top only work about half the time too. I think it's pretty obvious what my issue is, but my warranty's out.

I'm fine with opening it up, but not until I know exactly what to look for. Any help?