Since you are young, don't know your trading experience, but if starting out, cheap is best, ebay. What is most important is ram and internet speed for day trading.
Any computer will essentially do for trading.--these kind of computer/tech questions are weird...trading is not a complicated/advanced thing to do, tech-wise
...Just make sure you have any relatively modern, half-decent, computer that was purchased within the last four years or so.
Buy a Real computer though -- not one of those $200 Google books just meant for lightly browsing the web.
Noise is an important consideration when you are trying to concentrate. I bought an Intel NUC http://www.intel.co.uk/content/www/uk/en/nuc/overview.html which has one very small fan and can tun two or three 4k displays. It is very small.
I recently bought a refurb laptop for about 800$, normally retail around 1k from dell. Working great. You can also build a solid PC that works for years with 800$
Depends on your trading style tho, my laptop burn up when doing 20 charts. But I'm back down to 5 now. 20 is too much anyway. I'll never get those guys with 6 monitors and 30 charts, no way you can readily read all of it
Yes, but.... (1) you have to deal with compatibility of all the parts... may or may not be an issue, and (2) you have to deal with each part's individual warranty, should that become necessary.
Personally, I prefer the workstation route... Dell, HP, or Lenovo.