Of course Linux is going to install faster, it doesn't have all the integrated "crap" that windows has. However, I have used Linux, and it's nice when you have a little extra time to learn the ins and outs, but it's much easier...
There are some pretty good deals in the FS section, but if you want something new I would just wait for a Dell 1 day special and upgrade the video on it. They were doine 15" laptops for 499 yesterday.
Where are you at hitting 88C? if you are in a 85F house with your laptop on a pillow you'll start pushing 90C+... if you are hitting 88C in a 72F house with you laptop on a desk, then you may have a problem.
Sending stuff back... if you still have any accounts linked to dell they will charge it tot he accout after so long... but yeah, something like a whole laptop they will persue... a power adapter, not so much.